There shouldn't be any monthly fee to use Paypal. In general, the seller or recipient of the payment pays 4% fees of the amount received, or the buyer sends the payment as a gift and pays the fees themselves/forgoes buyer purchase protection.
May I ask where you heard about this monthly fee?
He's referring to the monthly recurring supportership for PC I believe, 1 dollar a month for Tier 4.
You have to sign up for that manually so if you just donate a bit now you won't be signed up for it. Although if you plan on donating anyway at some point you might be better off, because you'll have tier 4 perks while not having paid the 20 dollars for them until 20 months goes by, and then you can cancel the subscription and keep tier 4.
I don't follow. Are you saying that one has to pay for "premium" customer support? That doesn't seem ethical for a financial institution to enforce such one-sided policies.