OK.

1. Yes you can cycle animations in Maya, but I would not use that technique unless really nessecery. You can loose that control that you once had. Only use cycles if the animation requires it.
2. When rendering a movie it is always done as individual image files (targa, jpeg, gif, tiff etc...) then spliced together in a compositing package. A good free of is VideoMach.
3. Sorry not tried that, but a technique to use would be to model them in polys and then convert them to Hair or Model them in polys and use NURBS control curves converted to hair to control the polys. It depends on what you want them to do. Hey there might even be a version of that in Paint Effects.
4. This depends on what you are doing. For hi res characters you can just model them out and then model the clothes and convert to Cloth/nCloth and then do the required to both the model and the clothes to get them to interact.

Tutorials for both the cloth and the rendering techniques are available from the free section to give you a taster of what you can do.

Hope this helped.