You can sign whatever deal you want. I would imagine finding a gig that gives you 8 weeks off is touch 4-6 seems like it is more standard. All that being said though I have heard people with insane work schedules then a ton of time off. Whatever works for you.
Just remember that 7 12 hour shifts in a row in a place with any significant volume will kick your keister. Don't expect to do anything else that week except sleep, and you may be a little groggy for a day or two later.
Yes, you can get a lot of time off in EM, especially if you go somewhere where they need docs so much they're willing to negotiate. Usually if you're near a metro they have plenty of docs so the groups/chairpeople are less flexible.
The 7x7 shift sounds great! Of course I may get burned out on it after a while. I am doing my IM rotation right now and working 18 hour days doesn't seem like a big deal to me because as long as I am busy, I enjoy working. Of course the patient load in the IM compared to the ER is a bit different. I guess I'll find out more after I do my ER rotation.