Playing a 3 to the same suit flop

[rocflight]

Still early in the tourney with deep stacks. Skill level could be suspect because of low buyin. Minimal reads.

4 to the flop in an unraised pot including MP, button and both blinds.

Flop comes Q high all spades, SB pots it and only MP calls. Turn is Jh (no straight possibilities) and SB pots again, MP goes all in and is called.

Question is, the hands involved were J9s and QJo (no spades). Who had which hand? SB had MP covered.

Also, please provide how you would play this hand from the 4 scenarios.

1) play as SB with J9s
2) play as MP with J9s
3) play as SB with QJo
4) play as MP with QJo

What if this is late in the tourney where stacks are much shallower? What would be the change to the general approach?