i considered EM/IM and ended up sticking with straight EM, but i can answer some of your questions from what i learned when researching it
1. this will vary for each month based on what rotation you are in - when you are in the ED its 60 hrs max/wk, when you are on an IM or off service rotation it will vary widely based on the rotation. you will definately have more call months, both in house and home call if you do EM/IM than straight EM just because IM has more call than EM (obviously).
2. stress is up to you and your personality, only you can figure that out. if you aren't terribly insightful into yourself, ask someone who lives with you. i thought i was fine doing either, but my husband told me i complained a lot more when i was on my IM rotations than EM rotation - even though retrospectively i thought i liked both equally.
3. pretty much every residency has inservice exams every year to help you prepare for their respective boards - if you are doing a double-board residency i would expect you would have to take these practice exams for both each year (so 2 every year). this is completely guessing though.
4. depends on what you do - the guy i talked to was in academic and did a month of ED and a month of gen med wards, very little clinic. i think he was paid a little better than either alone since he was technically hired as a hospitalist and an ED doctor. the residents i knew who were graduating were getting hired for 250K+ jobs 1st yr out to do both just like that, one in florida and another somewhere in the northeast (Can't remember the state).
5. i was actually told by an EM/IM residency program director that the combined specialty is not more competitive than either alone because its such a niche specialty - people really have to want to do it. i think he said he considers interviewing anyone with a step 1 score >210 which seemed low to me. they are really just looking for people who have a solid reason and goal for doing EM/IM and know what they are getting into. its not for everyone.
hope that helps a little, if you are really considering it seriously i would sit down and talk to some residents in a combined program or a program director if you have the opportunity - i am lucky to be at a med school that has the EM/IM at the same place so it was pretty easy access for me.
