welcome to the world of hunting tree rats. when it comes to a firearm it all comes down to personal prefference. i will use a 410 shotgun during the early season when the trees are still full of leaves. later in the season i will use my 10/22. some folks will use a 12,16,or even a 20 gage while hunting bushytails. if you use one of those i would suggest going with #6 or #8 shot but that is just me.
most folks wear full camo while others will have some blaze orange... really dont matter because i have had those darn critters try to crawl into my lap during deer season when i have looked like the great pumpkin.
yes calls do work to some extent... i will use mine to try to get a squirrel to poke his head out so that i can get a bead on him.
all in all hunting squirrel,s is a great way to spend time in the woods and they taste great also
any other questions just ask and good luck to you and your wife out in the woods this season.