Is there any reference of temple of lord in the time of Satya Yuga? Around that time people used to worship which God/Goddess?
According to the Devi BhAgavata PurAna, there were temples even in the Satya Yuga. See the following passage. It also addresses your other question:
- Janamejaya said :-- “O Bhagavân! Describe particularly the details of the Yuga Dharma. I am now very desirous to hear which Dharma is for which Yuga?” 32-54. Vyâsa said :-- O King! I will now show to you by example the influence of the religion peculiar to each Yuga; hear it attentively. O King! The hearts even of saints are quite disturbed by the Yuga Dharma. See! Your father was a religious and high-souled monarch; still the wicked Kâlî defiled his mind and prompted him to do an act very insulting to a Brâhmana. Otherwise why would he, being a renowned prince amongst the Ksattriyas and a descendant of Yayâti, thus go and encircle a snake round the throat of an ascetic Brâhmin? Therefore, O King! All actions are being influenced by the Yuga Dharma. The Pundits, also recognise this. If you try your best to perform any religious act, even then the Yuga Dharma would prevail, yet you would be able to perform to a certain extent, a part of your intention. O King! In the Satya Yuga, the Brâhmins were versed in the Vedas, always devoted to worship the Highest Force, with an ardent desire to see the Devî; they were devoted to Gâyatrî with Pranava, devoted to the meditation of Gâyatrî, always reciting silently Gâyatrî, and the Mâyâvîja Mantram, the chief mantram. In every village, the Brâhmins were very eager to erect temples of the Devî Mahâ Mâyâ Ambikâ and were truthful, merciful and pure and devoted to their own respective works. The Ksattriyas, skilled in the science of the highest knowledge, were ever engaged in doing things ordained by the Vedas and were always intent in protecting well their subjects. The Vais’yas did their cultivation and trade and the S’ûdras always served the other three castes
I have highlighted the relevant portions.