swp is a swap file. img is an image file. Totally different things (sort of).
Too much vacant cache? That's like having too much money. If all of cache is vacant (IOW, 0 being used for cache) that's a good thing. (Actually it probably means that the phone isn't running, because
some cache is always being used, but the less being used the better.)
As far as Android memory management - let Android do it. Don't try to manage it yourself and don't run apps that claim to keep your RAM free of "unwanted" or "unused" apps. Read why in an article written by someone who wrote part of it
Multitasking the Android Way. (Being a programmer myself, I know better than to argue with a programmer about what a program she wrote does. It's like arguing with you about how bad your pain is.)