I'll be very happy to contribute - but I'm not comfortable with the idea of showing 'levels of financial contribution'. Specifically, if you're going to include that, I'd like the option to 'opt out' of being visible in that way. It goes against my grain.
I'd like to add my vote for PayPal as the main means to contribute, it seems to be pretty universal with people, and has its own options built-in for how people manage their contribution sources (bank account, credit card, no need to have a PayPal account to donate through them, handles different currencies well, etc.) so you wouldn't need to manage all that yourself. Of course, it might not be the 'cheapest' way to accept donations/subscriptions, but it's so easy to use that you might get more in the end.
I'm very grateful for this place - I've not been able to participate much lately, I've been too busy sorting myself out - but it's an incredible resource. It's almost the only site diverse enough to make me feel comfortable.