I have this exact rope and there are two black marks in the center of the rope.

From the Mammut ropes information booklet:
"All dynamic ropes from Mammut come with a friction resistant, coloured, middle marking. In choosing a process we made sure that a dye was used that wouldn’t weaken either the sheath or the core filaments. "

I don't have this particular rope, but all of the Mammut ropes I've seen (including the one I own) have two six inch (or so) long black dye marks to signify the (approximate) center of the line.

ETA: Unless, of course, you go for the Duodess model, which changes sheath pattern at the middle point.

This rope is fine, but thinner (and thus more expensive) than you need. I'd get something in the 9.8-10.2mm range, which will last longer and be cheaper.

All Mammut ropes in the Challenge Line, which are their top-end ropes (Serenity, Infinity, Revelation, Supersafe) have the SuperDry, CoatingFinish and DuraFlex treatments.

Super Dry treatment is Mammuts dry treatment where all of the nylon yarns have treatment to make the fiber not absorb water. Some dry tratments are applied only to the sheath yarns. Mammuts Super Dry is applied to the core and sheath

the grigri is fine to use on ropes above 9mm as long as your belayer knows how to use one, the thinner diameter will run thu the device if your not holding the tail end of the rope as for a non locking atc or something. i was being belayed by this guy on a grigri and he dropped me from 5 bolts up to 1/2 a meter from the ground on a 10 mm rope, when i protested what the f*#k he said, the grigri didnt lock off man.... i asked, were you holding the end of the rope he said, i didnt think you had to!! and this guy was quite an experienced climber! so now i always ask new belayers if they know they need to hold the tail end no matter what the rope diameter ;)

The infinity is fine on the gri gri, I've held many falls on this rope and it's no problem. There are many many out there who belay with the GG on Mammut's 9.2 and sterlings skinny nines and their still alive

Get a Mammut SMART belay device. It works on 8.9 to 10.5 ropes and is a super slick little unit. It pinches the rope and while not a true Autoblocking device like a GriGri it works like one and super easy to hold a fall. Best thing about it is how fast you can pay out rope for a lead belay.

I have this rope and I have used it with my Gri-Gri. It does work but I would suggest not using them. I don't like them in any situation though and an ATC is a much better option in my opinion. I used the Gri-Gri pretty much the same as an ATC locking it off like I normally would. Passive gear which you control is always better.

Probably not. I have a 9.8 that still grabs, but it's a bit sensitive. Hard to control the speed. I think this would be too small. The Faders SUM is an auto-locking device that grabs down to 9.1, I'd invest in that. Or a thicker rope.

This is a WAY better rope than you need. If you're not doing hyper-technical sport routes with big falls, this is overkill. Send it back and get something like a Edelweiss Ally or Beal Edlinger. In fact, get two for the same price as this rope.

It's a high-performance, lightweight lead rope, but it'll still be great for starting out. It might stretch a bit more than you anticipate though. Coolest wedding present ever.

The short answer is Yes but no. It will work great for top roping and alpine climbs but I would not use it for slot canyons. Canyons tend to have a bad combo: water and sand. Sand gets on your rope and works its way into the core quickly when water is added. I would purchase a canyoneering specific rope if I were you. Canyons will tear up most dynamic climbing ropes very quickly... Also for long rappels a static rope will allow for a much much smoother smoother rappel reducing the stress you put on the anchors which is very important with anchors in sandstone.