5/10 7 handed

SB - 1250 (tight image, only played & won 1 pot)
UTG - 1000 (fresh stack, aggressive, lost 2 big pots & got felted prior to this hand)
UTG+1 - 500 (new player)
HJ - 800~ (passive old reg)
CO - 1400~ (passive old reg)

UTG+1 posts 10
UTG opens to 45
UTG+1 folds
HJ calls 45
CO calls 45
BTN fold
SB calls 45 with AKJT
BB folds

Question:
1. Does SB have enough hand to 3 bet the UTG player (who could be tilting)?
2-4. What if the action was folded to SB? Do we 3 bet (get BB to fold) to get it heads up with the UTG player? Is folding an option if faced with a 4 bet?
5. Does position dictate most, if not all, what we can and cannot do?

Just calling cuts your variance a lot out of position. In the games I play in people that pot it just don't fold to a raise (doesn't matter what their cards are). While you are likely ahead there are a lot of flops where you are drawing thin/dead on low/medium card flops and being out of position sucks. I like to see the flop and play aggressively on those flops I flop well on. I'm fine with check/folding those flops I wiff on to further action.

So based on the information in the op.

3! Should be profitable, but not necessarily more profitable than flatting. A lot depends on how sticky all the players are.

If hero 3! And gets jammed on, he should stack off vs utg, but maybe not the other players.

You only have to worry about two passive old regs and someone who is tilted, so even out of position I probably pot this. It just depends on how passive the regs are and what they will call with if UTG just flats. I don't mind gii w/ UTG for 100bb.

I'm OK with flatting, though, if UTG is going to flat and the two regs are definitely calling.

I'd flat it and I'm a maniac

Completely depends on UTG tendencies imo. If he's the type to 4bet rip with random holdings when tilted, then I think it's a fist-pump 3ball. If he's likely to just flat, then I think calling oop and 3betting ip seems best.

3 bet all day

A case can be made for both calling and 3betting. I lean towards the idea that a player with a tight image should be more likely to flat and a player with a LAG image should be more likely to 3bet.

If UTG is likely to be over-aggressive on the flop and c-bet too much, I like letting him have the initiative and accepting good relative position while making it easier to avoid being trapped by the old passive regs. Are they the sort of old passive dudes where if you 3 bet and UTG 4bets, it would be unsurprising to see one of them jam with obvious aces?

1. definetely a candidate for 3betting

2. guy just lost 2 huge pots and obviously is on tilt so our hand is crushing his range, always 3bet, facing a 4bet i would 5bet shove against UTG just always against such player if he has AA so be it. We have a monster aswell.

3. in my opinion position is more important in multiway pots but in a heads up 4bet pot where the SPR is very low, I dont think it matters that much.

in a heads up 4 bet pot with a low spr i'd rather be out of position

If the passive old regs in this hand are just as aware as you are that UTG is on tilt, they could be on trap mode. When you 3 bet and UTG 4bets, I expect HJ/CO to sometimes shove an annoying percentage of the time if they are canny, old men who know how to use their image.

In multiway and/or low SPR pots, how you should play depends much more heavily on your cards. There are less opportunities for bluffs and fancy plays, which are aided by position. To put it another way, position matters more when you have options and your plays are not automatic, as they might be in a low SPR heads-up pot. If you 4bet with AAxx and have a pot-sized bet left on the flop, does it matter much if you have position? For most players on most boards, they are getting it in regardless of position. In a multi-way pot where the pot is protected by the existence of other players in the pot, you can't get too out of line because you will be trapped.