Heaters? I'd personally say two heaters (in case one fails), 200-250w or so each. I've read some "guides" that say you can use far less, but in my case that hasn't proven true. My 90g+30g+30g sump system has three 250s... because I've learned that if my house temp falls below 68 degrees, two 250s will not keep up (my wintertime tank temp is 76.5F).
I have had good luck with only two heaters... Aqueon and Eheim-Jager.
As for skimmers, that's about as bad as discussing religion.