[List]

You messed up #1 very very badly. Your reasoning is flawed. Plenty of people pot here with a full range of pat hands. You're missing on a lot of value since people have trouble folding pat hands, especially at lower stakes. Some tricky guys will stand pat with low trips here for whatever reason, but I still like a check raise.

#2 Edit: Misread hand, checking is fine post draw, but reraise more predraw. Btw, putting him on trips is pretty horrible here. Some guys will play some 2 pair hands like this, but won't pay off post draw. Very few decent players have a missed limp reraise with trips here, so a crap player with a draw is pretty likely.

#3 Don't lead out. Missed 4cds don't bluff much, especially 3 way, and most players seem to recognize that. You have trouble getting called by worse hands, and 2 pair will still look you up. Check/Folding is probably good here, unless you know that MP is a step worse than even his open limping indicates.