I would think that you would be expected to do a surgery sub-I as you're planning on going into a surgical subspecialty regardless if you do 3-4 ortho electives. I would be afraid that programs might think I was lazy if I decided to do a sub-I in family medicine instead of surgery. Although I did a surgery sub-I, I was able to get on to a very relaxed and easy service that required minimal hours, since I had already killed myself on my ortho elective and aways. I think that would be a better option than doing a family medicine sub-I, but others may disagree with me.

Pick the easiest one and do it after interview season. They will never know, nor will they probably care.

People ask a lot of questions about individual grades, but every school grades different, I really think the only thing they care about is your class rank and I don't know how much they actually care about that either.

I did one subi in September in inpatient general medicine. The medicine residents at my institution are great teachers, and I am friends with a number of them. I knew it would be a month I would 1) enjoy 2) learn a lot about patient management and 3) help prepare for the subi exam and Step 2 which are mostly medicine. The question of surgical v non-surgical subi never came up in interviews. If it had, I would have been happy to give my above reasons. Understanding primary care is important for an orthopaedic surgeon since that's the referral base for MSK problems, so I think you could make it a useful experience even if the hours are also good.

No reason to do a surgery subi unless you are thinking of applying for general surg as a backup. Do something easier like IM or FM. I agree with doing it really late if you just want to blow it off. It's also a good idea to schedule it leading up to step 2 CK or CS. I did an IM subi in Sept/Oct at a really easy site which was great because I was basically sitting at a computer all day and had time to respond to interview invites rapidly. I responded to every invite within a few minutes and got my first choice most of the time. It's very important to schedule easy rotations during these months so you can schedule your interview season the way you want and maximize your interviews. If you respond to an invite 10
Min late you will not get your first choice.

You will be asked about your ortho subis but no one will care about your IM, FM, surg, or Peds subi.

Nobody will care about non-ortho sub I. If they do (which they won't), Jayman gave you a pretty good interview answer. Avoid gen surg unless you have a specific reason (ie backup apps in gen surg). In my experience, gen surg residents can be a little jealous of matched ortho m4s.