1. - I have not tried it on a Pegas 21" specifically but it's my understanding that the hole pattern is the same. If it doesn't fit I would accept a return and refund you minus shipping costs though.
2. - The table doesn't tilt on these saws but instead the head tilts. But to answer your question it does affect the tilt to that side about the same as the stock one that came on mine did, which I think is around 30 degrees max maybe, but it's 4 phillips head screws to remove it. When I designed it, I had thought to modify it to not affect the tilt but in doing so it would end up sticking out from under the table and not be so tucked underneath. For me 95% of my cuts are straight cuts (not tilted) so it made more sense to have it tucked underneath more and just remove it if needed (like the stock one that came on mine). I hope this makes sense.
Maybe I could make a revision 2 version at some point that allows the tilt all the way but sticks out from under the table more so folks could have that option to choose from though. That's not a bad idea.
I'm also looking into a way to make one work for the older excaliburs without holes and the dewalt saws for future iterations.
I'm not doing this full time or anything and I'm not looking to get rich from it. I just designed something that worked well for me and thought I'd offer it to others. I already have a 3d printing store on Etsy (mostly ran by my daughter who lives with me along with my grandson as a way for her to be home with him) so I thought why not throw it on the store and see if anyone wants one.