As far as I know, in Vaikuntha there is concept of kainkaryam (service), is there a similar concept in Mani dvipa? What are the activities of Lord Shiva and Devi there? Is it that the goal of worshipers of Lord Shiva & Lalitha devi to reach Mani dvipa? What do they do there after reaching?
Bhagavatî is the name of the Devi who built Manidvîpa for her residence.
Vyâsa said :-- O King Janamejaya! What is known in the S’rutis, in the Subâla Upanisada, as the Sarvaloka over the Brahmaloka, that is Manidvîpa. Here the Devî resides. This region is superior to all the other regions. Hence it is named “Sarvaloka.” The Devî built this place of yore according to Her will. In the very beginning, the Devî Mûla Prakriti Bhagavatî built this place for Her residence, superior to Kailâs’a, Vaikuntha and Goloka. Verily no other place in this universe can stand before it. Hence it is called Manidvîpa or Sarvaloka as superior to all the Lokas......................
Devi Bhagavatî hears songs, frees Jivas from bondages, gives instructions on Jñâna, consults with Her ministers, the Sakhîs, Ananga Kusuma, etc., on the creation, preservation, etc., of the universe.
Vyâsa said :-- O King Janamejaya! The Ratnagriha, above mentioned, is the Central, the Chief and the Crowning Place of Mûla Prakriti. This is situated in the centre of all the enclosures. Within this there are the four Mandapas, i.e., halls built of one thousand (i.e., innumerable) pillars. These are the S’ringâra Mandapa, Mukti Mandapa, Jñâna Mandapa and Ekânta Mandapa; .................. Within the S’ringâra Mandapa, the Devî Bhagavatî is situated in the centre on an Âsana (seat) and She hears the songs sung in tune by the other Devîs along with the other Devas. Similarly sitting on the Mukti Mandapa, She frees the Jîvas from the bondages of the world. Sitting on the Jñâna Mandapa, She gives instructions on Jñâna, and sitting on the fourth Ekânta Mandapa, She consults with Her ministers, the Sakhîs, Ananga Kusuma, etc., on the creation, preservation, etc., of the universe. O King! Now I shall describe about the main, Khâs, room of S’rî Devî. Listen. The Khâs Mahâl palace of the Devî Bhagavatî is named S’rî Chintâmani Griha. Within this is placed the raised platform, the dais and sofa whereon the Devî taketh Her honourable seat. The ten S’akti-tattvas form the staircases. The four legs are (1) Brahmâ, (2) Visnu, (3) Rudra, and (4) Mahes’vara. Sadâs’iva forms the upper covering plank. Over this S’rî Bhuvanes’vara Mahâ Deva or the Supreme Architect of the Universe is reigning. Now hear something about this Bhuvanes’vara. Before creation while intending to sport, the Devî Bhagavatî divided Her Body into two parts and from the right part created Bhuvanes’vara. He has five faces and each face has three eyes. He has four hands and He is holding in each hand speer, signs indicating do not fear, axe, and signs granting boons. He looks sixteen years old. The lustre of of His Body is more beautiful then Koti Kandarpas and more fiery than thousand Suns; and at the same time cool like Koti Suns. His colour is crystal white, and on His left lap S’rî Bhuvanes’varî Devî is always sitting.
Manidvîpa consists of various places. The work by worshipers after reaching Manidvîpa varies from place to place. Worshipers reach Manidvîpa and after reaching they worship Devi, perform services to Devi, reside with the Devî in great joy and festivity.
S’rî Devî Bhagavatî dwells always in this place. O King! All the great Bhaktas of the Devî in every Brahmânda, in the Devaloka, in Nâgaloka, in the world of men or in any other loka, all those that were engaged in the meditation of the Devî in the sacred places of the Devî and died there, they all come here and reside with the Devî in great joy and festivity.
The devotees of the Devî, the Siddhas and the Devas and those that consecrated in their life times tanks, wells, and reservoirs for the satisfaction of the Devas dwell here with their wives.
In the centre is situated the garden of Pârijâta trees. They are filled with bunches of flowers. The fragrance of these Pârijâtas extend upto the ten Yojanas and gladden all the things all around. Those who are the Devî Bhaktas and who do the works of the Devî are delighted with this fragrance. The Hemanta (Dewy) season is the Regent of this place. He lives here with his two wives Saha S’rî and Sahasya S’rî and with his hosts. Those who are of a loving nature are pleased hereby. Those who have become perfect by performing the Vratas of the Devî live here also. O King! Next to this silver, there comes the eighth enclosure wall built of molten gold. It is seven Yojanas long. In the centre there is the garden of the Kadamba tree. The trees are always covered with fruits and flowers and the honey is coming out always from the trees from all the sides. The devotees of the Devî drink this honey always and feel intense delight;
There will be large number of different types attendants provide services to Devi's staying in Manidvîpa
.........Next to this Gomeda enclosure comes the enclosure made of diamonds. It is ten yojanas high; on all sides there are the entrance gates; the doors are hinged there with nice mechanisms. Nice new diamond trees exist here. All the roads, royal roads, trees, and the spaces for watering their roots, tanks, wells, reservoirs, Sâranga and other musical instruments are all made of diamonds. Here dwells S’rî Bhuvanes’varî Devî with Her attendants. O King! Each of them has a lakh attendants. All of them are proud of their beauty. Some of them are holding fans in their hands; some are holding cups for drinking water; some, betelnuts; some are holding umbrellas; some chowries; some are holding various clothings; some flowers; some, looking glasses; some, saffrons; some collyrium, whereas some others are holding Sindûra (red lead). Some are ready to do the painting works; some are anxious to champoo the feet; some are eager to make Her wear ornaments; some are anxious to put garlands of flowers on Her neck. All of them are skilled in various arts of enjoyments and they are all young. To gain the Grace of the Devî, they consider the whole universe as trifling. Now I shall mention to you the names of the attendants of the Devî, proud of their possessing lots of amorous gestures and postures. Listen. They are :-- Anangarûpâ, Anangamadanâ, Madanâturâ, Bhuvanavegâ, Bhuvanapâlikâ, Sarvas’is’ira, Anangavedanâ, Anangamekhalâ, these are the Eight Sakhîs. Each of them is as fair as Vidyullatâ. Each is adorned with various ornaments and skilled in all actions. When they walk to and fro with canes and rods in their hands in the service of the Devî, they look as if the lightning flashes glimmer on all sides.
...... The Sakhîs, attendants, the Devas and the Devîs surround Her on all sides. Ichchâ S’akti, Jñâna S’akti, and Kriya S’akti all are present always before the Devî. Lajjâ, Tusti, Pusti, Kîrti, Kânti, Ksamâ, Dayâ, Buddhi, Medhâ, Smriti, and Laksmî are always seen here incarnate in their due Forms. The nine Pîtha S’aktis, Jayâ, Vijayâ, Ajitâ, Aparâjitâ, Nityâ, Vilâsinî, Dogdhrî, Aghorâ, and Mangalâ reside here always and are in the service of the Devî Bhuvanes’varî. On the side of the Devî are the two oceans of treasures; from these streams of Navaratna, gold, and seven Dhâtus (elements) go out and assume the forms of rivers and fall into the ocean Sudhâ Sindhu. Because such a Devî Bhuvanes’varî, resplendent with all powers and prosperities, sits on the left lap of Bhuvanes’vara, that He has, no doubt acquired His omnipotence. O King! Now I will describe the dimensions of the Chintâmani Griha. Listen. It is one thousand Yojanas wide; its centre is very big; the rooms situated further and further are twice those preceding them. It lies in Antarîksa (the intervening space) without any support. At the times of dissolution and creation it contracts and expands like a cloth. The lustre of this Chintâmani Griha is comparatively far more bright and beautiful than that of other enclosure walls.