Welcome to the forum @Tyranosar, I’ve tried to answer a few more below!
See @greg’s answer above!
They will be utilising the Faster Payment system so deposits should be available the same day, see Depositing funds
UK residents, see Can people from other E.U. countries trade on the platform?
Not on launch, see Transferring portfolios from other Brokers
They would be open to these kind of integrations, see @adam’s point about Monzo here
No, see @adam’s point here about margin trading.
See this list of US stocks & ETFs that will be available in the future, you can make requests here Stocks/ETF Requests