On the timing issue, yeast in general and Belgians in particular don't work on time tables. They might rip away for the first few days, and then slowly chug along for a week or two at slightly elevated temps to get to final gravity. The only way to know that they are done is to get steady hydrometer readings. A Saison I did this fall with French Saison yeast (a real beast by all accounts) took two weeks to get from 1.060 to 1.010, and another week or two to get all the way down to 1.002 like I expected. A big point of "Brew Like a Monk" is that you have to get out of the mindset of two weeks at 66 degrees- you can let the temp rise over time, you might have to let it sit there for a while, but once you get the hang of it, you can produce some wonderful beers.
As for extra yeast at bottling, that Saison ended up sitting around for about five weeks before I had a day to bottle. Bottling day was a bit of a mess, as I had no sugar and had to use DME, which got a little syrupy in the boiling stage. Three weeks later, it has a lovely head. So you may be fine without adding more yeast- even after a secondary and a cold crash, I have had Belgians carb up just fine without adding more yeast.