Binance Futures Questions

Hello binancians, I just have a number of questions about futures (I have completed spot buying and selling a number of occasions but futures is new to me)

Can I've multiple positions in the identical tier e.g. multiple long positions in tier 1 on btc/usdt

AND

What happens once I attain maximum place e.g. does it set off scale back only/sell my position/nothing

AND

Should I exploit USDT buying and selling pairs or BUSD buying and selling pairs?

Thanks everyone