I have cycled around the Abitibi region quite often; I have lived there last summer, hanging out with a bunch of friends who are also the regional bikeheads/road race organizers/mountain bike trail diggers, etc. The "Route Verte" is one of the greatest project around here in Qc province, and I hope it will help us bikers to regain bits of our respect on the road. In Quebec city I have to say things have worsened between cycle commuters and regular trafic, but at least when you get out of the major towns, you go through a lot of quieter places where you can take the lane for cycling respectfully
I will have to go against michaelb05 by saying that the road 117 is not one of the best roads to cycle on, even it it's far better than the beatiful but utterly dangerous road 155. That road 117 is the ONLY road from the Abitibi region to the south, so most of the commercial trucks pass there. Yes there is an eastern access to the region (but long, remote and costly for commercial freight), and a western one (by northeastern Ontario), but most of the traffic use the two-lane wide 117. But, you have a huge shoulder, and in between Mont-Laurier and Val-d'Or, it's 297 km. So you have three days of not-so-pleasant possible encounters. That said, usually trafic is not that bad, i.e. you will have lots of trucks, logging trucks, and cars, but they might be sparse. You simply want to avoid the last two weeks of July, known here as the "vacances de la construction", where more than 75% of the people take their vacation, loading their fifthwheel trailers with the motorboat in tow. And, try to avoid taking that road in the weekend, as there are lots and lots and lots of youngsters driving fast, coming back to Mtl after a mine-shift, to crash into town, spend all their money and then speed back up (it's a 6h drive from Mtl to Val-d'Or).
So, if you plan carefully by avoiding weekends (let's say from friday to monday), and not going at the Vacances de la construction period, I think you can have a very enjoyable trek through the Reserve faunique de la Vérendrye, and the sights are plain gorgeous (if you like huge lakes and great sunsets along black spruce heads.) That said, for the rest of your trip, I'll try to answer your questions:
1- That part of the trail is half paved and half gravel, IIRC. At least for the part between the Parc d'Aiguebelle and Taschereau. I have not cycled it from Rouyn to the parc d'Aiguebelle, though. The terrain is hilly (Abitibi's kind of hilly, not Charlevoix :-), but rolling. The trail goes through the parc d'Aiguebelle, which is a pretty nice spot for hiking and swimming. Exiting the park on Taschereau's side also makes for one of the most beatiful countryside of Abitibi: rolling hills, small small roads (be careful, the pavement is AWFUL around Taschereau), forested lands, lakes and rivers. Almost no trafic, but always be aware anyway!
2- As said before, highway 117 between Mont-Laurier and Val-d'Or you'll have to be careful, but if you pick your timing right you will be fine. Some heavy freight though, but huge soulders and most of the time there is a third lane for passing that opens for automotive traffic. The part of that road where you don't want to be is between Val-d'Or and Rouyn-Noranda. That stretch is crazy dangerous, there is at least on car vs. car incident every week. Avoid it at all cost! Even by car, with the morning and evening rush hour, it's the worst place to be: reckless drivers speeding and passing even through very dense traffic, crazy bus drivers, heavy mining trucks, outcoming and oncoming heavy freight trucks, etc. etc. Highway 111 seems desert when you compare them to the 117! But, bear in mind that as there are way less traffic there, people tend to speed up also. Not not much heavy traffic there, most of it passes by the 117. As always in Quebec, pavement is badly worn out at some places, so be ready to grip your handlebars tight! You'll have a bit more traffic on hwy 109 between Amos and Val-d'Or but it's not that bad and it's fairly straight, with no huge turns or surprises, so trucks and cars can see you from a distance (it is also a bit boring, I have to say). Pavement there is fine, by Quebec standards again :-p
3-Yep, you are right. The reserve faunique La Vérendrye, along most other réserve fauniques, is the paradise of boating/fishing/hunting. It's a huuuuuge territory, with very few services. There are some campings, though, as michaelb05 said: Le Domaine (118km from Mt-Laurier, IIRC), Belle-Rivière (95 km from Val-d'Or). You will have more info on the Sépaq site (Société des etablissements de plein air du Qc - Parks Quebec if you prefer): http://www.sepaq.com
. Be careful when you plan your camping there, as only the road 117 is paved, all other roads on the Reserve are gravel and fire roads. Is it pretty? Well, don't hope for dramatic scenery, with huge 2000' cliffs everywhere, but, it is very nice and remote. Very typical of most of Quebec sights and nature: hills, sand beaches alternating with bogs or pristine rivers, huge lakes, humongous rivers (you will cross the start of the Outaouais - Ottawa river), might be windy, might not be. Trees, lots and lots and lots of trees, and a huge diversity of them: pines, spruces, birches, red maples. Mooses, deers, beavers, lots of birds, birds birds.
I don't know when you plan to do that trip, but a few more pointers: bugs! Be ready for bugs bugs bugs! It might not be too bad, but you can have bug attacks everywhere in Qc. As far as you go up north it worsens. Tundra bugs are infamous! I know it is not organic, but the best prevention is Watkins' cream, with 28,5% DEET. I have worked in forestry in northern Qc for 10 years, and that stuff works (don't make it go in your eyes, it hurts badly)! Otherwise, citronella is fine, but have a full pump before you venture there. Usually bug season lasts from late-may mid-june to late september. If you have a small breeze around it's fine (when cycling it's okay, but when you stop.....).
Also, temperature everywhere in Qc can vary very rapidly. And, as you go north, unexpected changes may happen.. fast! If you go in summer, you can hit 30 degrees C with high humidity days. Or you can also hit 8 deg. C day with rain and wind. A toque, wool gloves, good rain gear, along with light summer clothes are a must! Usually, may weather is completely unpredictable (-10 to +15), june also but usually a bit warmer (+5 +20), july is hot'n'humid (+15 to +35), august is sunny (+10 +25), september nights and mornings get cooler (+5 + 20; starts to freeze again in nights) but it's still sunny and you can feel pretty miserable in freezing rain in october, or in gorgeous sun and +10. Oh, and climate in western Qc is less damp than in eastern Qc, but that still means 800-900mm of precipitations all year long. Bring rain gear!
Phew.... long message! If you need more info, feel free to ask so!