1. I hope that your friend allowed you to shoot a couple of film holders to get a feel for the process, and even that you picked up the outfit and carried it and set it up.
2. Are you planning on shooting b&w and developing it yourself or shipping it out. What will be your cost for developing and printing, whether by yourself and buying the equipment and chemicals needed, or the cost thru others. If your going to do it yourself, add in all the bottles, tanks or trays, darkroom etc you'll need. If a student, figure your not going to be a student forever.
2A. If you are shooting b&w, which way are you going for enlargements? What will be your cost for enlarging it yourself or having others do it for you. What do you need to buy if doing it yourself?
3. Same questions as above but for color film.
4. How are your going to load your holders. A darkroom or a tent.
5. Time for a handheld meter.
6. A thousand can do it with one good lens, but it's not going to stop there. Forget three lenses for now. Pick your most used focal length and get the 4x5 equivalent.
7. If your not dissuaded, as a starter outfit I'd get a Tachi, your one lens, 4 holders, fast film, a handheld meter, lens shade, home made dark cloth, good enough tripod, heavier head, cable release and filters of your choice plus backpack. If you don't have access to a darkroom, or can make one, buy a Harrison tent to load the holders. Throw the camera equipment into your car on the day off of your choice and go shoot. Prepare for people really noticing you and wanting to talk to you or asking you to leave.
8. Hopefully you have a wife or girlfriend who will put up with your new obession on the weekends to go out....alone.