1.) There seems to be a bug with the new shower that came with Seasons. When it's present on a lot, Sims develop an obsession with showering all of the sudden. Take it out and replace it with a different one; should solve that problem. If not, invest in some skin cream for them; I imagine all that showering is going to leave them quite chapped.

2.) The fires are a result of our new annoying friend: spontaneous combustion. If a Sim gets too hot, there's a chance he/she will burst into flames. There's a hack at
SimWardrobe that'll get rid of that; look for 'No Random Bursting Into Flames' under 'Fixes.'
3.) Easy: the Penquin just wants that juicy looking fish! Just a bit of silly humor Maxis threw in. I've always thought it was cute.