Jobs / visa

Some people come to Japan with a visa in hand and a job set up. Others come to Japan, find work, then leave the country to get a visa and come back. If you want a specific location, which way is best? What if you have a friend in a certain city. Does that make it easier to find work there?
which method is best? What do most people do? If you first come to Japan, find a job, someone to sponsor you, and you can stay at a friends house, how much money should you have before departing? How does it take from the time you arrive till the time you have work and a visa?

Yes -- having a friend (and ultimately a place to stay) is key. VERY hard to rent in Japan, and almost impossible without a job. You're stuck to Gaijin houses. I'd suggest moving to your area, get a job (teaching probably). Get the visa, then start looking for a better job.

As for how much money you need, it depends on the area really. For Tokyo, a lot more than somewhere like Hokkaido. If you're planning no getting your own place, figure out how much you can spend, and multiply that times 6 for your first month (key money, deposit, rent, finders fee, etc.). Then figure you need food and furniture.