About bellows, you can only relay on them if you replace them. Not easy, or very cheap anyway, but possible. If I were you, I'd avoid using liquid laquer or paint or something like that, which in the long run may become sticky, collect all possible dirt and dust, your bellows may not fully extend and probably the adhesive may even "eat" bellow's material.
About lens cleaning, it is not that hard as long as you have the proper tools. If it is fungus and it has established itself firmly in the glass, solution for it may well be beyond DIY possibilities. Removing the lens is the easiest part, cleaning them (and learning from it) may or not be worth the effort, you should decide.
And about your particular model, without extra photos it's hard to say.