Could I condition my bottles at a higher temperature to achieve faster carbonation?
Is there any advantage/disadvantage to conditioning cooler and slower versus warmer and faster?
Are there temp. limits?
I’m still learning, but my understanding is that warmer temperatures can create things like fusel alcohols which give the beer an unpleasant taste (which will not disappear over time due to conditioning). The best thing is probably to wait until a week or more passes, though I will admit that one of my beers did carbonate after four days of sitting in the bottle at 70 degrees F. (Patience is easier to preach than practice, I guess…)
If your beer is not ready yet, what a great excuse to pick up a six pack of something new and different to sample in the meantime! I’ve got a six pack of IPA from Dark Horse Brewing in the fridge for just that reason… although now it is a three pack.
You’ll get so little flavor from the amount of fermentation that happens in the bottles that I wouldn’t worry about it. Warmer is better, up to the point that it becomes harmful to the yeast (which is at least 90°F).
The real trick is to brew more than your drink. 
The fusel alcohols and other unwanted byproducts primarily occur during the vigorous part of fermentation. The tiny amount of “fermentation” that’s going on during bottle conditioning shouldn’t generate those things. I’d go ahead and warm 'em up but, like someone else mentioned, keep it below temps that might actually kill the yeast. When I did it recently, the max they were warmed up to was 80-85 F. Carbed 'em up nicely, enough so that I went ahead and added them to my entries in the upcoming UMMO.
That’s been my experience too. I used an electric blanket to bring the beer into the 80’s and it carbed up completely in about 5 days. However, this beer was bottled very soon after primary and had not yet flocculated completely. No worries about fusels from 2 gravity points of fermentation IMO.
This is good.
I thought i might be able to force them a little but I didn’t know how much. Thanks.
I take it there’s no advantage to slower / cooler conditioning? other than slight ageing?
It really depends on the style, some beers absolutely must have aging to be at their best (Altbier, most any strong ale, most lagers), and others are best very fresh (Hefeweizen, hoppy beers IMO). The best way to find out is to try the beer after 1 week and compare it to 2,3,4 etc. weeks and see which one you like the best.
I have had very predictable and fast carbonation results using Kraeusen beer for priming. There is little or no additional yeast compared to conventional priming since the beer can be aged in bulk for longer. The carbonation times are generally 7-10 days and during the winter I also used a lager strain in the Kraeusen so the beer can prime in the colder basement.
Here is a write-up that also gives formulas and the procedure: Kraeusening - German brewing and more
I don’t bottle condition much anymore. Except for Weissbier where I still use this technique.
I wouldn’t let the beer get too warm (75 F might be a good upper limit) since higher temperatures accelerate staling.
Kai
This is a good point. Dr. Bamforth went over this in the Brew Strong episode on hot side aeration. Using the Arrhenius principle, he says that a beer that normally goes stale in 3 months at room temperature (~20C) will go stale in only 1 month at 30C. So a week at 86° (30C) can take 1/4 of the expected shelf life out of that beer.
I once ruined a Weissbier that way. Conditioned at 75 F (or even higher) and the beer was stale after just a month.
Kai