I have a Samsung front loader which I had over three years now. I love my machine and have not had problems with it (function, odor, etc).
1. I never use the steam setting so I can't answer that part.
2. I have added vinegar to both the detergent and the prewash section depending on what cycle I am running.
3. I use the SilverCare only on special loads - delicates and such. I hardly think using any setting constantly will break the machine, though.
4. I only found one brand of machine cleaner. I have also been known to just run Borax through a hot/hot cycle to clean my machine. I have never had problems with odor so I am not fanatical about cleaning it.
5. When I am not actively running my washer, I leave the door open. I may have clothes or something in the washer but I just leave the door cracked. If you are running the machine very frequently, you'll have less odor problems anyway. The odor arises from the tight door seal which when the door is closed, creates a good environment for mildew when the machine is just sitting idle.
The only other thing I do is periodically wipe down the washer door and seal with a cleaning rag with cleaner (bleach or vinegar or ammonia or whatever is on the rag). Basically when I get done cleaning the house and I am going to wash all the cleaning towels, I take one of the not so nasty cleaning towels and wipe down the washer door and seal. I toss in the towel - no pun intended - and run the load of cleaning towels.
We stacked our set by the way and that has been wonderful. I have so much more room in my laundry room. My husband is in the process of adding a set of cabinets where the dryer used to sit. On the cabinets I'll get a folding surface and a utility sink. Plus it will double as my craft counter. Very nice and space saving.