The motor does, in fact, sit a little higher compared to the stock mounts. Initially, that may seem like a bad thing. However, Nissan designed the mounts this way due to the fact that the majority of their customers lower their cars. Lowered cars means lower oil pan. I think you get where I'm going w/ this.
There are engine mounts that lower your engine for a lower center of gravity (ex. URAS), but that means that you're more likely to bust your oil pan, and blow your engine. I was planning on getting URAS engine mounts until this was brought to my attention by the manager Nismo (not in Arkansas, btw. . . lol).
The roads are pretty bad in AR, and the fact that the mounts were considerably cheaper than the URAS, I went ahead and got the Nismo engine and transmission mounts.
As for the shifter, the KA, SR, and the RB (except the getrag 6sp in R34 gt-r) are ALL interchangeable. This does NOT mean that they are the same parts. The RB25 & 26 shifter is physically shorter, and the rubber parts are more ridgid, however, it's not a short throw shifter, so the syncros will be spared the abuse. While I was home for the holidays, I went shopping

The stuff SHOULD be in within a about a month or so. The best thing of all, is that the shifter was CHEAP!!! It's just a Factory replacement part, so it's about half the price of Nismo stuff.
Pretty much anything Nismo will fit your S14. The only things that won't is the stuff that being right hand drive hampers (like floor mats, master cylinder stopper etc.) Of course, if you don't have the SR20 in your car, the engine parts won't fit either. One thing I'm not sure, however, is the HICAS stuff. I'm not sure the exact differences on the subframe are b/w the HICAS and non. But they have non HICAS S14's, so I don't think it'd be a real problem.