what kind of pot odds or relative stack sized do you need (preflop) if you have a few tight people invested heavy in the pot, so they must have premium pairs or ak? (i.e. you pretty much have to have a straight or luck out on a flush off the ak's color? I guess the strength of 78 is the implied odds - you can get them all in if e.g. qq catches another q but you have the straight.)

I like pots with plenty of people in them (assuming you can get away from TP). If you're playing heads up, the value of SCs comes largely from the ability to steal many pots, in addition to the hidden monsters - if you're not comfortable barrelling with air, I wouldn't play them except in cheap multiway pots.

In the 2+2 archive, there's a thread which suggests that the 5-10 rule still roughly applied to SCs, although you're folding plenty more in the interval. In other words, if a tight villain opens UTG, feel free calling in position if effective stacks are more than 20x the size of the bet, and sometimes anything down to 10x (although you need to be able to either steal a lot of pots or stack villain nearly 100% when you hit when you do get down to 10x).

You want 100bb effective stacks, so you have the implied odds. But I'd advise you to only play these hands - as a beginner - if there are at least two players in the pot and you are on the button. You should fold them in particular if you are in the blinds, as you just won't get the chance to extract any value when you hit. SCs are tricky hands to play. They may look pretty, but I fold them nearly always. Why play marginal hands like 78s that rarely hit big, when you can play solid hands like KQs+ and 99 that virtually play themselves?