Can't answer all of your questions, but will give you info on some:
I use PAYPAL because I use it for many other sites besides FC. It is easy enough to set up a personal PAYPAL account, but you need to have your PAYPAL account verified for FC to send you your money. And that takes several days, since PAYPAL sends a couple small deposits to your bank account and you have to tell them the amounts sent in order to verify your account (and you don't have to send the pennies back.)
Being verified means that PAYPAL needs to have either your bank information or a PAYPAL credit card so they know how to get backup funds if you want to withdraw or spend any money from your PAYPAL account. I've used PAYPAL for several years and have not had any problems with the integrity of that site.
If you are in a hurry to get your cash out request out today, then request a check be sent to you. I have never done this, but believe the check is sent on or before the 20th of next month so with snail mail you should receive it in 3-5 days there after.
You do need to have at least $25 in your account and at least $15 of that must be from offers. If eithor of these conditions are not meet, I suspect that the FC system will not allow you to cash out. Requests made in a given calendar month, if approved, will be paid on or before the 20th of the following month. (ie Cash out request today, 3/31, means payment on or before 4/20 if the cash out request is approved.)
The proof of payment section in the Forum shows pictures of checks received by members recently that are issued on a bank in San Jose, California. In 2007, there were check payments issued on Citizens State Bank in Clara City, MN.
I have found FC to be honest and reliable. I have had my cash out deposited to my bank account once. When I switched to PAYPAL, I noticed that my bank information was no longer shown so if I ever wanted direct deposit again, I would have to resubmit it. I have no doubt that FC removed my bank information completely.
You can change your method of payment with each cash out.
You can stop using FC in the future, but I'm not certain that you can delete your account.