Is there any way to use margin without incurring interest charges?, say I purchase 200 shares of stock with 2000$ of margin on the 11th day of the month, I then sell the 200 shares on the 12th day of the month and repay the margin, since margin interest doesn’t incur until the trades settle and I sold the stock and repaid the margin before the trade has settled will I still be charged interest on the 2000$ of borrowed margin?
...since margin interest doesn’t incur until the trades settle
That isn't correct. Margin accrues daily.
If you buy the stock on the 11th and sell it on the 12th, you pay one day of interest on your borrowing.
Some people sell box spreads (options) for a credit to generate cash but that's another story.
Yes, but only if you are (intra-)day-trading.
Your transactions might settle on T+1 or T+2 (depending on what you trade), but if you buy and sell on different days, they obviously settle on different days too.
You can also look into short sales and option spreads, where you generate extra cash before you use it - that cash is interest-free, but of course comes with other risks.