The FRB sets an initial margin requirement of 50% for the purchase of securities and it can be met by cash and/or marginable securities. Brokers can require more. .
The FRB's maintenance requirement for securities is 25% (brokers can require more).
The initial margin requirement for futures contracts can be as low as 5%
In all cases, your assets (...
Yes. You are correct. You can use margin like this no problem.
Just my opinion, you should go to a reputable brokerage like Interactive brokers. You know they will never make problems for you and they have the highest credit rating. It’s the safest brokerage in my opinion.
I have not heard of the brokerages you mentioned... maybe it’s good but I wouldn’t ...
Using an offshore broker circumvents the PDT rule.
Trading in a margin account in the US allows you to use unsettled funds, avoiding settlement date violations that could happen in a cash account. It's a de facto line of credit while waiting for trades to settle. I assume it's the same offshore.