pretty easy, would recommend that you go and see the OC of the unit you wish to transfer to first and find out all the units committments etc. If you are happy you can tell him you want to transfer from your old unit and their clerk will probably do the rest. Bear in mind the PSAO/OC of units will probably check up on your attendance/record etc.
Yes but that's not quite as simple. Firstly how old are you? If you're still in the age limits for direct entry into the Regs who told you you couldn't rejoin because of the cuts? (because frankly thats not true).