i'm not an expert on UV mapping, but in terms of getting the textures, i can point you in the direction of cgtextures.com, who have thousands and thousands of very good textures for free download, and you can either apply them directly to your model, or edit them to suit your preferences first. the only limitation is that you're not allowed to download more than 15MB from them in a 24-hour period. i usually find that's plenty.
if i need to edit the texture, my program of choice is GIMP (
www.gimp.org) - it's got a slightly weird layout, but it does pretty much everything you could want an image editing program to do, and it's free. it's quite easy to use after you've had a practice session or two. it also has the advantage that it was clearly developed by people with a sense of humour - in the default installation, one of the available paintbrush settings draws peppers instead of standard lines, and there's a size-and-resolution preset template for a square of toilet paper... i think it's brilliant: a program that is very powerful and can do all the serious stuff, but has a little humourous edge too.
i'm sure someone will come along and offer advice on UV mapping sooner or later, but i hope this helps for starters.
- colclough