Replying to Bike people - i have a question

here's the deal. i know absolutely nothing about bikes, whatsoever.

a friend of mine has an old road bike he's trying to get me to take off his hands. however, two of the gears in the back are totally bent, and the back rim is also bent. i have another friend willing to give me a wheelset for a couple beers or something, so the rim isn't the issue.

my question is, how hard would it be to convert that bike to a single speed, so i don't have to deal with fucked up gears and other things that can go wrong?

the new wheelset has a freewheel on it so it should be no problem making it a single speed.

there are 3 gears on the front pedal part with a gear guard on the outside. would i need to do anything with those?

i also know i have to shorten the chain since it wont be going through a derailleur.

any other insight is appreciated. thanks.