As it is my first post, I would like first to greet the community ! I've been reading since few days different threads and I'm in the mood to create a new one !

So from scratch :
I've been doing mainly spherical panoramas with a 550D + a canon 10-22mm 3.5 and lately with a samyang fisheye 8mm 3.5, the new ones without the hood. My panohead, well, doesn't really worth to talk about it as it is a chinese piece of junk bought on Ebay for a very reasonable price ! In the mean time, that's why I'm here ; because I seriously want to upgrade my gear as I do more and more panos.

So, I need some advices because there's few things I'm not sure to catch. As I was reading some threads, I've seen some inputs saying that it is more recommanded to use a RS1 (or now RS2) in order to make spherical panoramas, the R1 being not that great to shoot Zénith with a single row.

So my question is : with that tilt option that the R1 offers, is that possible to create a spherical panorama with the following "settings" ?
-A full frame body (canon markiii)
-A samyang 8mm
-The R1 head
-A first row of let's say 3 shots every 120° @ -7.5
-Then a second "row" tilting the head @ +12.5 and making let's say 2 shots every 180°

Does tilting @ +12.5 will be enough to get the zenith. I would say yes as using a fisheye on full frame is supposed to give me a 180° FOV right ?
I would be very glad if anyone that have a similar gear/way of shooting could advise me.

Other thing I'm don't really understand. In the R1 spec of Nodal Ninja website it is said :
-8 precise on-the-fly tilting options (-15, -10, -7.5, -2.5, 0, +5, +7.5, +12.5 deg)
-Ability to roll the camera/lens in any position including the popular 0, 60 and 90 degree positions.

I'm not sure to understand the last one vs the first one. What exactly they mean by "roll" the camera ?

I've tried to find some videos in use of the head to have a better idea but to be honnest, I haven't found one ! Anyone here could share some usefull ones ?

Thanks for reading ! and hope I've been enough clear !
Cheers to all