To replace the chain and guides you have to remove the lower timing cover which means you need to remove the vibration damper and hub. The big hub nut can be a pita depending if you have the right tools as it's VERY TIGHT !
You need a 3/4 drive breaker bar, matching socket with a big tube to slip over the breaker bar handle for extra leverage or a decent air wrench type thing.
Once the nut is off you will need a hub puller, you might be lucky and just be able to pull/gently lever the hub off but all bar one out of four hubs i've had off needed a puller.
The timing chain guides and the oil chain tensioner are just held on by some little circlips so come off easily.
Cam sprocket is easy as it just bolts on but the crank sprocket is heat expanded on to the end of the crank, i've never replaced one so i'll let some one else help you with that.
Oil pump change will need the sump to be removed(or lowered out of the way ?), once the sumps off it's fairly easy to swap pumps. The oil pump is not re-buildable as far as i know ?
I would get the head checked out properly by an engineering shop, explain whats happened and see what they advise. It's going to be hard to decide about which head gasket to use till you know what state it's in ?