You can use a debit card on the Gemini exchange to place instant and/or recurring orders (depending on your location).

Limits

There is a limit of $1,000 when using a debit card to place an instant or recurring order. This limit refreshes every 24 hours. 

Fees

Please refer here for fee details.

Gemini’s trading fee schedules are publicly available here, and you should see the fees you’ll be charged when you place any trade on the Gemini Exchange.