If your soil is good and gritty, Pixilady, then decent, gritty potting compost is all that should be needed. If you are buying your new plants in from a garden center they are quite likely to be growing in peat. I would clean as much of this as possible off the roots and then put a John Innes type of compost in the growingh hole to plant them in.
That was the easy part of your question! We have a whole garden full of alpine and similar plants and bulbs - there is no such thing as favorite ;-). If pushed, well, Saxifrages would come high on the list and yellow Drabas also make nice cushions. I like the small aster family like the alpine asters and Erigeron, and, for some colour into autumn there are the summer flowering Gentians.

You have a terrific choice, Pixi, but I love Lewisia, Hepatica and Iphion. If you look under 'A' at the bottom of the page, and click on Alpines, you'll get masses of ideas.

Thanks (a bit belatedly) Bulbaholic & Sheilabub-I shall definitely see if I can find some of the varieties you both recommend. My local nurseries have the more common alpines of which I've bought a few so I'll have to look further afield or get to a Plant Fair! There's so much to do in the garden in the spring thats it difficult to prioritise jobs-I just need more hours and more energy!!

If you rally want to spoil yourself I expect that many of the specialist alpine nurseries wiil be at the AGS shows:
http://www.alpinegardensociety.net/shows/dates-and-venues/

Our alpine bed is now fully replanted & is looking really good - I don't think I have anything really unusual in it but lots that I've not grown before & although I've said its fully planted I still have 2 or 3 plants recently bought that are waiting to be planted!