The best songs i found when 1st starting off, or when my legs have had a break and dont like double bass anymore were Guns N Roses "Paradise City" and Whitesnake "Give me All Your Love Tonight" - do those alternating your feet for each beat so your legs are getting an equal warmup for the standard patterns then when the double bass bits kick in you should really notice an instant improvement in how your feet work with you and the rest of the kit. Its great for seperation and equal strength.
Then when you can do those with an easy as pie attitude, go for Motley Crues "Live Wire" and as you said "Red Hot" just for endurance so you know you got this shit down - if you keep messing it up, then just go back and keep going through it until your nailling those bass drums with all your heart everytime and you dont even have to think about it anymore. When you can use the legs like the arms - move onto the Slayer stuff and you'll no doubt have a nice smile on your face as you can just breeze right through it all.
Better to build a house on concrete than slap a mansion on sand you know.