hi
applelaine, will try to answer your questions the best i can ^^;
For BJD purchases (locally, since you don't mind secondhand) you can check out
http://community.livejournal.com/bjdasia for secondhand dolls up for sale. Alternatively you can also check out here on facebook:
http://www.facebook.com/group.php?gid=317687585948Brands wise, well, there's a lot of brands out there ^^;
Several things to take note about BJD:
1. Resin type. French, urethane resin? French white or tan or normal skin? There are pros and cons to different resin types (I can't remember all details exactly but they react differently to our humid weather) and french white resin tends to yellow faster than other resin color/skin tones.
2. Mold. Most of the time we tend to get the dolls cause we find them looking irresistible on the website. Try looking through several photos of the same dolls belonging to different doll owners beforehand, it helps. One doll can look very different with different type of faceups and styles (I'll get back to you on the first one later).
3. BJD joints. Depending on the manufacturer, not all BJD are extremely flexible. Bobobie and Custom House dolls are the few manufacturers that I know whose dolls are not very...flexible. Double joints allow the dolls to pose better (or lets you pose them more realistically).
4. Size. Which do you think you will be comfortable taking care? 60cm? 40cm? 26cm? Or the challenge, 11cm? Look through and you'l somehow figure it out on your own

Ok enough on that, I tend to ramble hahaha. To answer your question, face-up is the 'makeup' that is applied on the doll's face to give them a completed look. Kind of like applying eyeshadow/eyebrows/lips and realistic skin depth to your doll's face

Hope that helps!
But anyway, just to ramble a few doll companies that is worth a look for a first doll (please google them up):
Angel Fantasy
Iplehouse
LeekeWorld
Luts
Bobobie
Angell Studio
Angel of Dream
Impldoll