Re: Question about omote and ura...
Although there is a pretty important semantic difference between omote and irimi as well as between ura and tenkan, most dojo I've been to do not differentiate between them (eg omote == irimi, ura == tenkan). So, for the questions that you asked, the answer would be pretty much "yes."
However, as Janet pointed out, the meanings of the terms are quite different.
The way I treat them is that omote and ura describe nage's location relative to uke's front center-line whereas irimi and tenkan describe the movement that nage takes. For example, I can do an irimi movement to uke's ura (as in most instances of iriminage) or I can do an irimi to uke's omote (like in shomen ate). Similarly, I can do a tenkan to uke's ura (like for some instances of kotegaeshi) or I can do a tenkan to uke's omote (like the opening movement in yokomenuchi shihonage).
... all of which is probably more than you really wanted to know...