How long does bank verification take with PayPal

The costs are absolutely nothing.

By allowing PayPal to use your bank account, you are saving PayPal money - they don't have to pay your credit card company a transaction fee. That is the preferred mode of PayPal nowadays and they are doing their best to motivate people to finance their PayPal accounts with their bank accounts.

From my point of view, I'd rather use my CC and have another entity I can appeal to between PayPal and my money. But again, this means PayPal's cut from each of my transactions is lower (not that I care about it).

I have verified mine with just a credit card by following the "Add a credit card" option - just gone in and checked it now. The process involves PayPal charging a nominal small fee to the card, then you enter the code that will appear on your statement.

They still would prefer me to add a bank account to the details page (they offer to lift receiving limits if I do this) but my account is verified purely from the credit card validation.

(Caveat - I am in the UK. Rules may be different)