I guess various kinds of mesh will work, but we used to use a polyester mesh (which came in various hole sizes, depending on ink used and effect desired).
Some people who make smaller frames/etc for screen printing may even use various polyester mesh fabrics like those for wedding and fancy dresses (organza) and even curtain "sheers," etc.
I think you need to ask these questions in online forums that deal with screen printing, or at least look online at some of the info:
.... http://www.craftster.org/forum/index.php?board=346.0 (all Image Reprod. bds)
.... http://www.craftster.org/forum/index.php?board=8.0 (only Clothing-Reconstr. bd)
You are better off buying the frames. One of the most difficult parts of making the screen is stretching the silk(no longer real silk) It needs to be done perfect or it will never work right, if it is too tight it will pull and rip, possible skew print, too loose and it will not print, it will only make a mess and ruin a couple of dozen shirts. You can find them relatively inexpensive from Dick Blick art supplies also Pearl Paint is a good place....
I really recommend not making your own screen....
As for getting the image on there...if it is a photo or really detailed use photo emulsion to shoot image onto screen( I would only done this if you are familiar with the process or real technically apt)
The other way is an adhesive film that you apply to the screen after you have cut your image out of the film(tape image on table tape film over it) film. This is an easy process but it stinks rank chemical smell from the adhering fluid
stick with nazdar inks I have found them to be the best
after printing hang or lay flat too dry...some people heat cure but it can be complicated....
oh and place a piece of smooth, thin, cardboard in the t shirt, larger than the print, smooth so there are not any bumps before printing