Hi Weetbix
I like your route 2 better as well, but it does push the timing pretty close. That would have to be your call. In August I would expect to have stable weather and not need to plan in extra time to wait out any storms, but this year has been really weird, and you just never know. As a backup / last resort plan, I would think it would be pretty easy to hitchhike if you run out of time, lots of people drive pickup trucks and could give you a ride. I haven't ridden the area around Colorado Springs to Salida, so I can't add anything about that.
For your first question, I haven't been on that road, looking at it on google maps does look like it's dirt, and the only thing I could find searching about it made it sound like it's dirt. Some of the forest service dirt roads in CO are just fine on a tour bike. It sounds like this is a well traveled road and they are applying Mag-Chloride, which means it should have a fairly hard surface, but may be washboarded. Hard to guess. I would call the county
http://co.grand.co.us/departments.html http://co.grand.co.us/R&B/MAIN.htm
For your second question - well, Junction -Mesa - Cedaredge - takes you over Grand Mesa, which is absolutely fantastic, but is also one of the biggest climbs in the state. from I-70 it goes up about 6000' in 20 miles, then you roll along on the top of the 10,000' plateau for 10-15 miles, then drop down the other side into Cedaredge. I have toured this, and it's fantastic, but that route would add probably one or two days. To get there from Junction you do have to ride on I-70 for a little while, which is scary. There's only about a 3-4 foot shoulder. There is a lodge on the south end of the Grand Mesa plateau, but at that point you may as well drop down to Cedaredge. There are campgrounds on top of the mesa, with water, but other than that lodge no where to stay indoors. Looks like there is lodging in Mesa (one lodge) and Cedaredge. Verify this, I don't have first hand knowledge. I know there is a big convenience store in Mesa, and a tiny town.
I would say, the better re-route would be to take 50 out of Junction to Delta (heavy traffic, huge shoulder, likely afternoon headwind), then instead of going to Montrose go to Hotchkiss or Crawford (small, but there may be lodging in Crawford). Then take the 92 past the north side of the Black Canyon to hook up with 50 to Gunnison. I have been on this as well as your origianal Montrose route, both are hilly and challenging, but the 92 through Crawford is very remote and beautiful, with almost no traffic, where the other is on Hwy 50 and has quite a bit more traffic. 50 is safe enough there, there's a shoulder, but it's not as nice. 92 is one of my favorite roads, I have ridden it in both directions and would do it again in a heartbeat. There's a marina where it joins 50 at blue mesa reservoir, where you could get a snack and refill water. By mid afternoon you should have a roaring west (tail) wind on 50 into Gunnison.
There is a great hostel in Leadville.
If you do your 1st route and have extra time, there are 2 route alternatives that add climbing and intersting passes, if you want more:
from Leadville, go to Minturn then past Vail, over Vail Pass (super awesome bike path) to Frisco.
From Frisco, head over Loveland Pass to Georgetown then over Berthoud Pass past Winter Park to Granby.
Lastly, on your last day into Boulder, the route you show is absolutely a fantastic one, but it does have a hard climb up out of Estes Park, an easier way which is still very nice is to head northeast out of Estes Park past Glenhaven, then down Hwy 34, to CR23 and follow that down to Boulder.
Here are all the alternatives I mention on a google map
http://goo.gl/maps/Nh9a