Once I started playing I felt like this cause I was traveling alone, but once I started meeting people I began to have a good time and enjoy it again. It's just a small phase man, you'll get out of it soon.
Crawlers are already there. You just have to disable a zombie and it will start crawling. Looks creepy as hell if you're not expecting it.
Didn't even know that, thanks for the heads up dude. Gotta try it out soon and see for myself.