Simple, Secure Online Donation Form.
Yes, setting up a Donately account is free and can take less than 5 minutes.
Donately is integrated with Stripe & Authorize.net - you can use an existing account, or create a new one.
Yes. You will need to enable CIM if you are using Authorize.net to process for you.
There are no monthly fees from Donately, but there is a small (under 2% average) per transaction fee. You gateway will also charge a small transaction fee (around 3%) for processing credit cards. Authorize.net charges a $20/monthly fee for enabling CIM (needed for recurring transactions).