I can help you with a few of those questions, but not all:
1. you send the sponsorship/perm residence forms all together. you make the payment online and send the receipt (this, is what i believe)
medicals and police checks should all be done before you send the application. if you don't send everything together and wait till later it will only slow down the application process
2. if you are sponsoring your spouse/partner you do not have to have a specific income. i am unemployed and still going to sponsor my boyfriend
3. outland is always faster. we are doing ours through Sydney Australia and believe the wait is around 7 months. i haven heard people say buffalo is quick quick for American's applying through there.
4. you can join the buffalo group on here, they will help you.
5. a pretty broad question. as long as your relationship is genuine and they don't see it as a union of convenience and you are not on welfare or bankrupt.(and there are other requirements)... you need to read the application packs cover to cover they really help. the more evidence you provide the better...
6. be honest, provide lots of proof, leases, letters from relatives, pictures, joint bank account info, emails, boarding passes etc
hope that helps! this forum is great, so read all they different topics, they really help.
good luck!
so i have to send in medical results/ recipt and fbi clearnce with the forms and everything?