Mechanics and Fixing Any Questions Answered

if you don't do this sort of thing often and the bottom bracket spins without play, then just leave it well alone. spray some gt85 in there if it feels a bit stiff but otherwise don't touch it. it could well be a problem as they can seize and be nightmare to get out, even people who know what they're doing will groan at the thought of fixing one. if it aint broke, etc

it looks easy and cheap to me otherwise.

if you're set on keeping those wheels, you'll likely need long drop callipers, any levers will probably be fine. I would put 27" wheels in there, as it probably had originally just as it fills the frame better.

take the outer ring off if you want to keep the inner one but you will probably have to put a spacer in the chainring bolts. just use 5x M10 washers, you might have to trim an edge to fit. otherwise buy smaller bolts for a single chain ring.

all a single speed kit is is a sprocket with spacers, you may have a sprocket and spacers kicking about already in the form of an old cassette, so try that.

buy a 1/8 chain online for a few quid.

get an old MTB from the dump for spares such as riser bars, pedals, etc.

should be fine, you shouldn't have any trouble. all the above are just suggestions if you want to do it as cheap as possible.

if not just buy a load of bits and get spendy