No coins, it's too much of a hassle to manage and far from being a stable market. Also use the bank account only if necessary, transfer fees will steal more money than paypal will.
If you're going to donate through paypal, please use the PitchIn! widget in the sidebar it will save us a lot of time.
Also, if the donation bar is at 100% you can still continue to donate, when the month ends that money will be added to the next month's progress bar.
Is some currency preferred (euro or dollar) for donations or it doesn´t matter (because pitchin show it in dollars, but server is in Europe so paid by euros I guess)?