Ron, I just read the manual for the Hyperions and like the way they work. They seem to offer a lot of flexibility. And the reviews on this line are good for slower scopes, which mine is. But will the use of rings and removal of the first lens set interfere with field of view and eye relief? The manual isn't clear about this.
No, they don't affect anything. If you read the chart, you will notice that the FTR shortens the focal length of each eyepiece. So the 21mm with the FTRs would become a 14mm eyepiece. And if Baader actually made a 14mm Hyperion, it would look exactly like the 21 with the FTR - basically, shorter focal length eyepieces are physically longer in length in this design.
But to be honest, I wouldn't get wrapped up with the FTR right away. Try one or two "straight" and see how you like them first. There is plenty of time for experimentation later on.
I don't know how big your budget is right now, but the Hyperions are on sale for $119.00 each at Agena Astro and that is a great way to get your feet wet. Personally, I would start out with the 24 and the 10. Those are two general purpose eyepieces that will get a lot of use in your 100ED and you can go from there.
There is literally a lifetime's worth of things to see with your 4-inch refractor and a few Hyperions.