A:AnswerYou have plenty of room for technically any card, nothing really abstracts back or top. I have tuf gaming rx 5700 xt (long one) and it has no issues. I could even squeeze RX 570 with riser in addition to card on board. Pretty decent.
A:AnswerThe case should come with the necessary motherboard screws for you to use on your device. If they were not included or they do not fit, I would recommend contacting Dell customer service to verify the correct screws for your respective motherboard as it is an older one and wouldn't want any other screws messing it up.
A:Answer330mm fits fine, but there is no provision for drive mounting behind the front panel. Drives are mounted in the basement or behind the MB tray.