Hey Mike, I know I caught ya' over on Adv. Rider, but I'll cross post my answer here as well, for this group to see....
...actually, it's Batopilas Canyon that you'll be going into....
I'll try to answer your questions in order....
For some background, when I did it, I had pretty minimal dirt time; having just purchased my first bike less than a year before embarking, so the entire route is possible for a novice rider who has some dirt time (I'd done Baja and some roads around Arizona). I'd recommend TKC 80s or similar, but that's just me. Other members of my group did just fine with Michelin T66s, but they had significantly more dirt skills than me.
1. The route down into Batopilas Canyon, to the town of Batopilas is about 50 miles of dirt, and took our group about 4 hours; stopping for pictures and going about 15-25 mph. It's a decent road, of course, the drop offs can be intimidating; but if you keep your speed down and watch for oncoming traffic it's not a bad trip. Elevation in Creel is about 7000'...Batopilas is about 1500' or so.
Usually, riders go "down" to Batopilas, then have the option of going back "up" to Creel the way you came in, or, as we did, heading towards Tubares and Creel. This back road, consisting of 100 miles of dirt, is much more challenging than the primary way in, with about 1/2 being rough dirt/silt/rocky conditions; culminating in a river crossing of the Rio Urique (no bridge). Depending upon the season, the river can be waist deep and impassible, or, as it is most of the time, calf to knee deep.
The latter half (Tubares to Choix) is a newer gravel road built by a mining company. Other than the use of every conceivable type of loose surface, with some silt beds in the corners, it's not bad at all. Our good riders could do 50+ mph on it....me, I'll stick to 25-30mph.
2. I have a map and some GPS points for the towns. If you'd like, get me your snailmail addy or a fax number and I'll send it to you.
3. Creel to Batopilas took our slow group 4 hours.
Batopilas to Choix took our slow group 10 hours, so I'd plan a full day for that one. Others on AdvRider can do it in 1/2 the time....
I suppose there are places (Tubares) where you might find a room with a local, but I don't know of any hostels or motels on the way. It's not really an area I'd particularly like to camp, but in a pinch would....lots of mj farms in the canyon....
4. ....when you say "motor scooter" I'm assuming it's a Honda Ruckus or one of the bigger jobbies...so if I'm wrong let me know.
The main issues would be suspension damage, tire/rim failure, or other get-off related issues, such as a broken lever. If you go from Batopilas to Choix, some of the canyons you'll be crossing (I stopped counting at 11 I think....) are very steep and rocky uphill and downhill sections, where I was standing on the pegs and bottoming out the suspension of my R100GS. A couple of drop off ledges did hit the skid plate. I'm looking forward to having the extra suspension travel and lower gearing of my R1150GS Adventure for this trip.
I'd consider using a skid plate if you're doing the back way....going in and out shouldn't be an issue....just watch the clutch if it's an automatic scooter. Take extra tubes...and even an extra tire if you can't find heavy duty ones.
Let me know if you have any other questions. I'm happy to help.
-H-