BB(520) is an old man, he seems like a bad player but I haven't been able to quantify how exactly he plays badly. Sat down 3 orbits ago.

HJ(covers) is 32ish white guy in a button up shirt. Seems like he may be competent, he just sat down an orbit ago and hasn't made any bad plays.

Hero(900) is young Asian male. Been playing TAG. Have only shown down strong hands.

2 limpers, HJ raises to 30, Hero calls with KsQs, BB calls, both limpers call.

Flop(150): QJ4r
BB checks, check, check, HJ bets 85, Hero tanks for 1 min and calls, BB calls, fold, fold. I think BB would overcall with just a Q.

Turn(405): Jd - puts up a diamond draw
BB checks, HJ checks, Hero tanks for 1-2 min and bets 220, BB calls, HJ folds.

River(845): 7d
BB shoves 270. Hero folds.

Questions:

Is the flop a call or fold?

I don't think BB or HJ checks less than a J on the turn. There is a significant chance HJ is ahead of Hero. It will be tough for HJ to continue against Hero with one pair given their stack depths. Should Hero turn all of KQ- into a bluff here? If so, what size bet?

Is the river a call or fold?

Preflop and flop are fine. Preflop, HJ would have to be very tight before I'm considering folding KQs from button. On flop, you can't give up TPGK to a single bet that could be a c-bet with air.

The turn is more questionable. When it's checked to you, it's slightly better then even odds your ahead. However, your not getting better to fold to one bet. A bet here is mostly about protecting your equity, you can charge a lot of possible straight/flush draws here. With two villains you don't have a good read on though, I would much check here.

River is a trivial fold despite the pot odds. When the BB calls half of his remaining stack on turn your done with hand without a specific read that villain will chase for terrible odds. The river just closes the case because the diamond draw got there, if by some chance you where not crushed on turn, your beat on river.

I'm assuming you were either CO or Button by the action; I would prefer to 3! preflop with hands in the top 5% of your range. Action certainly would have changed and you could have avoided the flopped set of 4s and took a nice pot from the HJ.

Trying not to be results orientated but I think checking back turn is the play. Let either V bet river and keep the pot small because your hand isn't as strong as you think.

Flop is a call for sure.

I'd prefer a check on the turn here too. Draws call and hands that beat you call. However I think the risk and reward of checking/betting balance out to both of them being close to equivalent (check slightly>bet).

Also, be aware of what your 'tank' represents when you do it. Your tank on the flop will help you rep a jack harder on the turn, but your tank - bet on the turn looks like a lot of draws. Most people will think that you are weak when you tank.

I hope you didn't seriously tank for a minute on the flop...

Easy call on flop.

Turn I prefer a check. I understand the logic of the bluff, but:
1) you're often ahead anyway
2) someone else could easily have a J
3) people will often call you down with AQ/AA/KK thinking their check induced or you're overplaying a Q.