1. The period of ashaucha (sutaka)
In the case of death of a person (normal person of old age, not being children. In case of children rules are different), the relatives known as Sapindas (defined below) are affected by ashaucha (sutaka), irrespective of whether they were near the deceased person at such time or not. As per the Vedic Kalpasutras, the impurity due to death lasts for 10 days:
Referring to deaths and births, they declare that the impurity of Sapiṇḍas lasts ten days
- Bodhāyana Dharmasūtra Praśna I, Adhyāya 5, Kaṇḍikā 11 (Krishna Yajurveda)
It is ordered that impurity caused by a death shall last ten days in the case of Sapinda relations.
- Vasishtha Dharmasūtra Chapter 4
The impurity caused by death lasts through three nights; Through ten nights, according to some (teachers)
- Pāraskara Gṛhyasūtra Adhyāya III, Kaṇḍikā 10 (Shukla Yajurveda)
Though sometimes texts mention different periods of ashaucha for the 4 different varnas, a common practice is accepted as 10 days for all.
2. Sutaka for relative in a different place
As far as the death of a relative living in a different place is concerned, the ashaucha is to be observed from the time of hearing about the death till the time of expiry of the prescribed 10 day period. However in case one hears of the death after 10 days have elapsed, then the impurity is to be observed for 1-3 days:
If one dies while being absent on a journey, (his relations) shall sit (on the ground, as prescribed for impure persons) from the time when they have heard (of his death), performing the water libation (at that time), until the period (of their impurity) has expired;
If (that period has already) elapsed, through one night or three nights.
- Pāraskara Gṛhyasūtra Adhyāya III, Kaṇḍikā 10
He who hears, within ten days, of a relation resident in a foreign land having died, shall, remain impure for the remainder of the period of ten days.—(74)
If the period of ten days has elapsed, he shall remain impure for three days; but when a year has elapsed, he becomes pure by merely touching water.—(75)
- Manusmriti Chapter 5
The same finds mention in the Kurma Purana too
3. Rules to be observed in Sutaka
The person following the rules of Sutaka must eat food procured from outside, sleep on the floor separate, eat saltless food and refrain from non-vegetarian food (no meat).
Through a period of three nights they should remain chaste, sleep on the ground, do no work and charge nobody (to do it for them).
Let them eat food which they have bought or received (from. others); (they should eat it) only in the day-time, (and should eat) no meat.
- Pāraskara Gṛhyasūtra Adhyāya III, Kaṇḍikā 10
sit during ten days on mats, eating food that does not contain pungent condiments or salt.
-Bodhāyana Dharmasūtra Praśna I, Adhyāya 5, Kaṇḍikā 11
A similar list find mentions in the Garuda Purana also the the extras being following Brahmacharya, refraining from physical contact, donation and educational activities
As regards a rough idea Sapinda relation, it extends to the seventh generation i.e. six generation above and six generations below a person (father’s side). People having a common ancestor 6 anywhere till six generation above. (Ref BDS 1.5.11). For unmarried girls, it is based on lineal descent but in the case of married women it is the same as the husbands Sapinda relation (Ref. Kurma Purana Chapter 23)