Disagreed. As I have two GSM iPad 3's, I could directly compare the memory usage of 6.1.2 to 7.0.4 on them. (See my dedicated benchmarks here at the iOS7 forum.) I didn't find much difference in the free RAM available after booting in.
Hmm, definitely not my observation. I used to be able to run airvideo in the background on my iPad 3 while surfing the web or playing a game. Couldn't do that after iOS7.