do i need to pause my timer between levels?

nope pepega

Yes, but this process is automatic using the feature built into livesplit. Inside edit splits, enter the game name and click activate.

with autosplitter feature can you have a separate timer for your IGT to run along with RTA?

https://github.com/Dalet/LiveSplit.AlternateTimingMethod/releases

Download this and add it to your livesplit layout