Wow, that's a heckuva friend!  Nice gift.

Yes, this is something you can easily do yourself, or have your LBS do it for you.  If you know what you're doing, it only takes a few minutes.  If  you don't know what you're doing this will take a few minutes more, but it's something you can definitely do yourself.  Unless you actually blow up the hub you can't do too much damage to it.  At the very least, take it to the LBS and have them look at it, and maybe make sure you have the right tools.

Most of the wrenches at the LBS are happy to share the wealth of knowledge.  Even moreso if you are willing to say thanks.

As far as which type of shimano hub, I'm confused.  Mavic has a freehub converter you can buy from Mavic.  I would suggest that one.  I assume you're going from campy to shimano?  SRAM and Shimano use the same freehub.  If you're referring to the cassette (grouping of gears) to put on said hub, I would suggest the same gearing you're currently riding.  If you're going to climb and depending on what kind of gearing  you have in the front, I would suggest a 12-25 or a 12-27.  Are you a good climber now? If you're a good climber now, you can probably get away with a more aggressive gearing.

Does that help?

CT

Larkspur-

No problem.  It's kind of silly that SRAM and Shimano have been able to figure it out, but campy has to be "that guy" and wreck the whole works.  It seems like it would make more sense to just make that freehub universal, right?  People that get paid more than you and I no doubt are making that decision.

It looks like you already have the bible for bike repair, and I'm not sure what else I would suggest.

Like I mentioned, most of the wrenches at the LBS are happy to help.  If they're not, just try another shop and don't return to the first one.

The one point I would make about bike maintenence is know when you're in too far and don't be afraid to ask for help. The truth is, you can really muck up some parts, and it's more likely the more expensive parts are going to fail before the cheap ones.  I worked in a bike shop for a good long time during my formative years and I learned quite a bit.  However as technology changes and improves, I know my knowledge is a bit dated.  The fellas at the LBS know me by name because I try to ask before I blow it up.

Lastly, about learning this stuff, just ask people what they're riding and if they like it.  You can learn a lot about that stuff by just being social.

Good luck and post how it went!

CT

Larkspur,

How did it turn out?

CT