Tip: If you make a change to your ROM that you regret, just go to File > Restore > Restore ROM to Previous State in the menu. From there, you can select a restore point and revert your ROM to a previous state.
Yeah, I've had a lot of problems, but I think I've got everything working properly now, on the level importing side of things. Toad's Tool on the other hand... I just can't figure out how to use that thing. It's the most unintuitive program I've ever used in my life, and I haven't been able to find any decent tutorials at all. =/