we have a 1-2 game with lots of bad players (most of which are reg-fish)
there is a straddle , an open to 25 and 3 callers. stacks are at least 5-600 and some of the callers have 1000 or more.
the stradle is fairly passive and not raising without 99+, AJ+.

how light can we make a call in the buton and in the small blind in order to play profitable 4-5 way (or sometimes more) and what is the critical number of players in the pot at wich the range increases (or decreases).

I'd like if you could type in the whole range (top and bottom) in order to better visualise the line between folding calling and 3betting.

really depends on the table dynamic and the initial raisers image.

how is your answer of any help?
if you just say it depends on other factors you could try typing some ranges for every type of situation that you consider.

If the table is loose and stacks deep you got to play tight in order to make money.

AK

Not sure if your only playing AK is facetious, but does the fact that 25 will get three or more callers open up the range a bit on the button. For example, can you play j10s+ profitably since you are getting laid such good odds when it gets around to you?

What you should have is a low variance winning style. Of course you can make money with a high-variance too if you know what to do. The hand JTs is great if you don't have to pay lots to see a flop. When you flop an OE almost never get the correct odds to draw. The price will force you out of the draw.

AK

When stacks are deeper and you are looking at a multiway pot, you need to have a hand which can make a monster. Suited connectors, suited gappers and small pocket pairs are pretty unfoldable.

Playing tighter when stacks are deeper is really bad assuming we have any post flop reading edge and our opponents are incapable of folding premium starting hands when faced with huge post flop bets. When you are up against a really fishy player who has got lucky and amassed a huge stack you should be looking to get involved in as many spots as possible which could result in you doubling up through them.

how about offsuits? how low would you go?

You need to use more detail if you want a solid answer. Saying, "Hey guys, here is my game please do the work for me," is not going to cut it. How about you write out in detail the scenarios you encounter, post some ranges you think are good and then ask people what they think about it. The discussion would be much better that way.