You can take your car to an advanced auto parts (or probably any place) and they have a machine they hook to the battery to test it and the alternator. My girlfriend had a Subaru Legacy 2.5GT and the battery light came on the dash. They ran about a 4-5 minute test and told me the batteries fine, but the alternators not putting out a sufficent charge (hence the dash light). I bought a reman from them for about $100 after the core charge and the problem was solved (the one I pulled off was a reman too though, so there must be an issue with that car, she sold it since).

Anyway, long story short, you can test the alternators output to see how healthy it is, most auto parts places will do it free hoping you'll buy your new alternator from them. I don't know the average lifespan of a fuel pump, but I haven't heard too many stories about them failing either.