Opp: CO: 80/4, 1.3, 51 hands.
MP: unknown

1) Am I committed here against this opponents with half stack?
2) What about this 80/4, 1.3 opponent with 100bb stack?
3) What about 25/15, 2.0 regular with 50bb stack?
4) 25/15, 2.0 regular with 100bb stack?

$0.25/$0.50 Pot Limit Omaha Hi
5 Players
Hand Conversion Powered by weaktight.com

Stacks:
UTG ($19.95)
CO ($21.15)
BTN ($20.20)
SB ($9.50)
Hero (BB) ($25)

Pre-Flop: ($0.75, 5 players) Hero is BB A 5 J 4
UTG raises to $1, CO calls $1, 2 folds, Hero calls $0.50

Flop: 5 K 5 ($3.25, 3 players)
Hero checks, UTG checks, CO bets $2, Hero raises to $6.50, UTG folds, CO goes all-in $20.15, Hero calls $13.65

yes
no
no
no

as I see it, it comes down to the cards villian is holding.

if villian has KK** or K5** you are in pretty bad shape. lets say when he holds one or the other of these hands you have 15% equity.
if villian has K*** you are in pretty good shape. lets say you have 75% equity.
*** if villian has any4 or A2** for example you are in even better shape then 75% equity****

to call his all in 3-bet, you need to call $13.65 and when you win you win ~$29 so you only require greater then 32% equity for the call to be +EV.

if villian has KK** or K5** less then 70% of the time and K*** or worse all other times,(more then 30% of the time) then you have greater then 32% equity to make the call.

as to considerations whether villian has a 50bb or a 100bb stack....as you only have a 50bb stack --the effective stack is 50bb as long as villian's stack is equal to or greater then yours
when it is 50bb effective stacks, you require greater the 35% equity to make the call, as you will be calling $17.50 to win when you win ~$32.85.

as to considerations of villian's vpip...does the vpip measure whether he plays a hand with a K or a 5 or KK...i don't think villian's vpip is very relevant here.

When I wrote "100bb stack" I of cause meant effective stack.
And of cause I understand that after my check-raise I committed with 50bb stack sizes.
Here, when I make check-raise, I make it to get value from opponent's weaker holdings. If I think my opponent will not call my check-raise with weaker hand than I have not any reasons to check-raise, because he will never fold better hand.
So the question is do I need to check-raise in this four situations to get value?
And what is my best line for flop, turn and river If check-raise is not good decision for this four situations?

i think you should be leading the flop if you also bet worse than three fives (ie bluff, and this is perfect bluff texture)

The way you played it, you lose the max when he has KK and K5 and you chase away a lot of other hands. I would much prefer to bet/call the flop and then do something on the turn.

If you did check the flop then I prefer to just call when he bets (intending to check-call again).