How to modify a stage or properly transfer texture and palettes (new to hacking)

[gary oak]

I'm new to Brawl/PM hacking, and I would like to modify this Battlefield stage to be closer to Project M's (meaning higher platforms and less wide edges to the point of only being slightly longer than the 2 further out platforms): http://forums.kc-mm.com/Gallery/BrawlView.php?Number=203134
However LunchablesTX told me stage modification is the most difficult aspect of modifying Brawl, so if actually messing with  Scout's/xxWutzMercyxx's stage and modifying collisions and models is out of the question, i would like to know how to properly transfer textures to PM battlefield and delete unnecessary background elements, as well as implement palette settings that are in WutzMercy's stage. are there any guides/pointers on how to go about this?