For 2, wouldn't most of that memory be either COW or physically shared, read-only? It's been about a year and a half since I've operated a large PHP site, but I don't recall the apache workers getting anywhere close to 15MB each, unless a request was operating on a larger than normal dataset. (this site used curl, gd, memcache, uuid, pspell, tidy, soap, and probably some others I've forgotten, loaded dynamically.)