Technically..
1. A C41 color film(a.k.a normal films) is called a negative when developed.
2. A E6 transparency film (a.k.a slides) is called positive(u can see the actual colors from it) when developed normally.
3. But when u cross process ur slides, it is correct to be called negative.
And yes.. u can print them out from any photolab.. Just bring along ur negatives(if u have already developed them) or cd (if u got 'em scanned) and they can print for u. (: