There are plenty of recipes for paper developers that you can mix yourself. I like Ansco 130 the best. It keeps very well, so you don't need to constantly mix up new, and it has some of the nicest tones on the warm tone paper I like. The recipe is posted in many places, but here's one such link: http://www.apug.org/forums/viewpost.php?p=1371914

I don't know how readily available the chemicals will be in Pakistan, but I imagine you could mail order them.

I personally don't think 4x5 is big enough for contact printing, so before you get setup for this make sure you will be happy with the 4x5 inch prints. If I had limited space I would go with either a medium format system like a Hasselblad and a smaller medium format enlarger, or an 8x10 camera and make contact prints. It really depends how you want to work. I know it's heretical to say on this board, but you can also produce excellent work scanning and printing digitally. I still like darkroom prints better, but at some point the reality of space and chemical availability must be factored in.