Go bigger as much as you can go. Remember that a bigger tank will require more $$$ while a smaller tank will require more maintenance. Its better to have a smaller tank with proper maintenance instead of having a bigger tank which you can't maintain. Don't always listen to "go bigger". But yes, go as big as you can afford and keep up with. Going with bigger tanks certainly has many advantages like more water = more stability and wider selection of fishes that you can't have in smaller tanks. You just have to make this decision depending on what you want to give to it
And regarding skimmer questions, there's a member named "skimmer king" over here; the name says it all
