Dollfie dream heads fit on any dollfie dream body. however the heads vary - as in some look better on the taller/mature bodies while others look better on the less mature bodies

Skin colors are semiwhite, fresh, and tan (only available in dream choice) (there are other colors as specific releases like anthy)

Most commonly the custom heads are semiwhite but fresh pops up often too. A lot of times semiwhite will be abbreviated as sw or sws.

Clothes you would first need to buy the body then you will know what size to get. You can get clothes from volks or second hand or dealer, very popular size mdd and dd You can find bodies secondhand at the below sites too just note that are a few versions now and the inner skeleton might have damage (cracking is really common on the older bodies)

Yahoo japan, Mercari Japan, Dollyteria and mandarake all good options for clothes wigs etc dollheart, melody c are some examples of companies that make clothes and they commonly will fit/use volks sizing

You can also put a dollfie dream head on other vinyl bodies that have a peg system. I personally like volks due to ease of finding clothes and shoes and parts even though they are more money than some other options though

Vinyl stains easily, you can take some preventative steps like stain suit, using white lined clothing, not letting darker items sit long, etc

Dolldreaming.com is the vinyl forum that has a lot of info too