Here are some questions you should be asking yourself to figure this out on your own:
What handrange do you expect the donker to have?
What hands do you expect the other player to fold to a flop raise?
What hands do you expect him to have that are better than yours?
Given #3 and #2, would you rather the SB call, or have him fold?
How likely do you think SB is to donk again if you raise the flop?
If you knew SB would fold no matter what, would you call down vs UTG?
1) Ok, for the donker I honestly don't have much of a clue. If's he capable of limping in UTG, then AJs or K4o wouldn't suprise me. As for what he would donk, I'm think Jx hands, small PPs, some 4x and 2x hands, and some flush draw/straight draw hands. However, the presence of the third player makes me think UTG is a little more likely to play his hand straight forward.
2&3) the small blind cc's, and I would imagine thats a little bit stronger of a range than the utg limp, but if I raise, maybe he folds a PP between J's and 4's? Maybe some 4x hands, but that's about it for the better hands than mine. I'd imagine the majority of hands he folds are worse than mine.
4)...I don't know? I'm not happy if he fold QTo, but I'm pretty happy if he folds 55 or 47s.
5)...Do you mean how likely is "UTG" to donk again? (and by "donk again", I'm assuming you mean if I do go ahead and raise here)...I would imagine given his capacity to utg-limp and donk, he's pretty random in some of his decisions, but more likely than not to donk again (let's say 75-80%? and probably less likely to donk if an A/K/Q comes and doesn't improve himself)
6) If SB folded would I call down UI? Well I likely only beat busted 's, so If Im calling down, it's not when one hits (though I obv's peel if a club hits the turn).
As for a first hand with a new player, I suppose there is some merit to showing down and taking a note, but perhaps if he's this recreational of a player (utg limp...) then its likely he's just going to give money away for the rest of the session. What made me interested in fighting for the pot is the 7 little bets pre (plus his donk, so 8 little bets), and my backdoor draws.