Do I need to do anything special to make sure my fondant snowman keeps standing upright? Should I push a skewer or something through him? He only needs to be about 3 inches tall, nothing huge or fancy. Thanks!

if it's going on the top of a cake, I'd put a skewer through him....if it's going on the sides of a cake I wouldn't bother.

you can use half a mars bar for a snowman, at my decorating class w did snowmen father christmas and angels using this method, use a circle cut with the garret friller and use edible glue and stick the mars bar to it,just an idea for you hope it helps.

Make the snowman, I think he's pretty okay. However, he is "melting" or looks like he is. I'm sure this is a dumb question: should I have combined something into the fondant? It must be the weight causing him to squish, but I'm not sure what to do about that. (Thank you for the Mars bar idea, I need to look into that)

Maybe some tylose in your fondant. I made some trees once and they were kind of saggy even when I tried to use skewers to hold them. I mixed some tylose in with my fondant and they held their shape better and dried hard.

if you can't get your hands on any tylose then next time use half gumpaste/half fondant if you want to minimize the squishiness.