well last night i experimented and put each song into the same session, each within its own respective folder. so i can have the freedom to mix each song individually and also freeze/render stems to save cpu. but i have each song fed into MAIN busses, like Drum bus, Guitar bus, bass bus, vocal buss, samples bus. that way It gives me the ability to keep just the levels of each MAIN group the same for each song, while being able to automate/EQ/tweak the songs contents individually in each songs folder. i guess this works for me right now, and I only have 4gB as well, no issues.