Leverage and Margin (Dollar Neutral Strategy)

I am having a hard time understanding the margin and leverage on equities. I have a margin account so as I understand it, Interactive Brokers gives me 2 times overnight and weekend leverage.

If I have $1000 in my account, can I go short $1000 worth of stocks and long $1000?

Or I can only go long $500 and short $500 because of the Reg T margin requirements.
As I understand the requirement, you have to post a margin of 150% for short positions and 50% for long positions.

Thanks for helping me figure this out, folks.