Answering my own questionsAndrey said:Not sure how long should I wait to keep this chain powered to get info and how powerful my PSU should be.
1) no longer that 5 seconds
2) 2A PSU is enough
3) BMS only required
4) Power both +12 pins (4 and 5)
5) Ground to any of 6-7-8 pins
Not sure how accurate reported VIN then - for some reason it shows me some strange VIN from 2012 (Japan) while battery is definitely 2014 (2 power sockets vs 1 on 2012).