Fairly New to Bitcoin - 3 questions/topics I need to learn more about + good discussion!

1. Is trading Bitcoin derivatives legal in the US? If so what are the best exchanges? I have experience in equities and FOREX markets so interested in learning how all of the products compare in terms of product/exchange functionality
2. I saw on Coinbase has offerings to borrow against your BTC. Has anyone tried this? Any strategies? In theory, their 8% APY 1 year notes are easily covered by the % increase in BTC/USD. I know the point is to never have to sell the underlying asset therefore never triggering a taxable event but it seems like there is definitely a strategy here to build your nest egg while using the loan to cover expenses/etc... this is done all the time against traditional securities.
3. Additionally on Coinbase they have a debit card. Although I would rather not sell my BTC eventually we will use it for purchasing everyday things. Any advice on this product? Does it treat the outgoing cash as gains therefore taxable each time you use the card?

Any additional advice on tax liability reduction, asset management, etc...trying to create a more long term strategy more than just HODL...I am not that new.