Use the free agent list. Coaches will check this list as we get close to the season start, and have until week 3 before rosters lock. Get on the list, be patient. You can also go out to the games during week 1 to try and see if you can get on a team.
Pay the registration deposit ($200). Check the registration tab for details.
FOr the regular season - yes. All teams make the post-season, and you will play in "A", "B" or "C" depending on how you did during the regular season. The Virginia and Maryland leagues all play in one big post-season with A, B and C level.
Riverview Park in Ft. Washington - check fields tab for details.
You will need flag belts (sonic pop/boom type), a football, and at the minimum (if you do not want to go out and get numbered jerseys or shirts) white t-shirts with numbers in marker on them.