A similar carburettor and engineering skill.
Basic automotive tools and a new carb to manifold gasket.
No, you do not have to remove the engine to replace a radiator hose.No, you do not have to remove the engine to replace a radiator hose.
Take the engine apart. There is no reason to replace the chains unless you are overhauling the engine, normally.
It would take seriously expensive modification
what sort of fuel system? carburettor or electronic injection?
you just unscrew the muzzle brake and replace it with the silencer
No!
Take it out and put a new one in.
Take it to a mechanic.
With another engine ready to go, 10-12 hours.
It can be done in an 8 hour day. It depends on what year, make, model, and engine.
take the oil pan off the engine and then unbolt the oil pump from the engine.
In short you have to take the head off, replace the gasket/s and replace the head. You best bring it to a pro.