A:AnswerYes, depending on what CPU you use this board supports up to two M.2 drives. https://www.asus.com/us/Motherboards/ROG-STRIX-B450-F-GAMING/specifications/
A:AnswerThough yoy will not get any bennifit from pcie4 it will work fine. The xt series are the only ones on the market with pcie4. I have a 5700xt in mine no problems. Also no benefit. But its a great card
A:AnswerI can't say definitively but I just ordered this a few weeks ago and it shipped with the latest firmware meaning it is ready for the newest chips (AM4). I have read that Asus is including the latest firmware but it really depends on how long the item has been out in the supply chain before you get it. With Best Buy I have always had good luck though.
A:AnswerB550 is primary for 3rd gen ryzen most 450 and 470 are currently 3rd gen ready should have a sticker on the box but some require update. I have this board and it did not reauire update to bios but just beware that is its old stock it may yet require a update. Btw this board is great minus power delivery is a bit shaky..