Posting bb, after rebuy., adding chips

1.If I lose my entire stack in cash game and rebuy I have to post a big blind. I should be able to play without having to post bb.

https://www.replaypoker.com/hand/replay/215174760
In the hand above, I lost and I rebuyed and had to wait or post bb.

2.Another issue is that I have to sit out, if I want to add some chips. Normally I should be able to click add chips option at any time, and chips should be added next round.

3.Biggest pot rank in a player’s profile should not involve tournament hands.

I agree with your first point. I think it is strange that you have to post the blind even though you did not miss your blinds.

Agree with 1 & 2 but why for 3

Tournament chips don’t have any relation to your bankroll. You can have a bigger pot, by playing in a tournament with 1k buyin, than by playing in a 1 million buyin tournament.