Danaher to Spotted Bear is two full days at typical July levels (ie 2-3300 cfs @ Twin Creeks). For example, this past July I floated from the White River mouth to Spotted Bear in one day, which amounted to nine hours of rather focused effort. Danaher itself will be slow, as will either hiking around Meadow Creek or scouting a bunch if you run it. Budgeting 2.5 days would be advisable. Much below 2k cfs, Danaher and the part of the South Fork above Big Prairie will be quite slow. Also, keep in mind that at any of these levels floating speeds will increase significantly below Salmon Forks.
The turnoff of the trail up towards Limestone is obvious, as is the first mile or so. The trail is faint but clear all the way up to the summit, though there are a few spots through meadows when it's vague. The game trail down from the summit and up towards Ibex is plain to see, and right up near the ridge. The trail up towards Ibex is used by horses in hunting season. Once up high the terrain gets rocky and the trail is harder to see, but line of sight route finding is simple. Going under the flanks of Silvertip there's only one way to go, and a good game trail throughout with occasional signs that it was once a maintained horse trail. Once over the pass, stay high and hikers left until you can eyeball a clear shot down to the trail.
Trail signs in the Bob are irregular. Generally, they exist when they are least needed (ie obvious junctions). I've missed several turns by walking right past a junction in the woods, when the trail was not much used and the sign was tiny, sunbleached, and covered in moss.
The USGS streamflow site and various Snotels can be used to generate graphs of (respectively) when in past years the rivers rose and fell and what sort of snowpack said activity was correlated with. Mid-early July really is a safe bet. Flows could range quite a bit either side of normal, but you can count on floatable levels regardless, short of armageddon.