Am I able to convert my Buff points to Apex coins?

Yeah you can get Apex Coins with Buff Points, easiest way I've found is to get Apex on Steam - it wont reset your stats - and buy Apex Coins by filling up your Steam Wallet with a Steam gift card, by spending Buff Points. You wont be able to get any mythic items though, you'll need heirloom shards for that - which you cannot purchase for real money.