Many of the Colorado outfitters will run a training class, usually in early May. They charge around $500-$600, it lasts about two weeks for paddle, less for oared. The WW shops will mostly be paddle, the oared shops will mostly be fly fishing outfitters. Colorado has a state certification process that she will have to complete to guide, and it should be the basis for any outfitter training. If they can't offer the state cert, she needs to find another shop. Sometimes, but not always, the outfitter will pay back the $500, if the student ends up going to work for them. They will probably also want her to complete Swiftwater, and she will need current CPR/First aid.
Usually, the classes cover the same runs the shop will do during the season. Most shops have enough turnover they will need to pickup at least a couple of newbies. As to the number of days/miles/runs lots of variables. There are years when some of the commercial runs are no-go, either because of too little, or too much water. A cold snap can last a week or more, and few clients show up to be cold and wet. Last I checked, most guides got paid per trip; first years around $30 per trip, max of two a day, not including tips. Bad weather, no trips, no pay. Never heard of a guide getting benefits, but I guess it could happen.
Most of the runs are covered by some form of Federal permit. Outfitters are limited by the permits they hold, and on the number of boats/clients they can launch in a day. The rich get richer, and the startups struggle.