1) "can these damage my pc" Yes.
2) "Are these power surge protectors any good" Also Yes.
3) "recommend a particular model" Belkin have a good reputation, but I've got a few different brands about the house and fingers crossed they all do the job.
4) "could be fitted into my main fuse box" Not that I know of, but I'm no electrician. Anyway with the models I use, bad power surges kill the protection as they're self sacrificing devices and would need replacing. Most have a status indicator light, if it goes out get a new one.
5) "to protect both my computers and other electrical equipment" the ones I have are in the form of multi socket adapters and can be used on any piece of mains equipment you want to protect.