I always pitch my lagers at fermentation temperatures. Actually, I pitch all of my beers at fermentation temperatures, or even a bit below. So, I when I make a lager, I chill the wort to 50 degrees, and take the starter out of the fridge (where it's been for a day or two, finished) and bring that up to about 48 degrees and pitch the slightly cooler starter into the wort. That seems to work great.
As far as raising the temperature after primary for the diacetyl rest, it's best to do that when fermentation is about 75% finished, so the yeast are still very active. So, if your target FG is 1.016, say, and it started at 1.060, I'd do the diacetyl rest at 1.020-1.022 or so. That will encourage the yeast to clean up the diacetyl as well as finish up the fermentation. Sometimes I miss that, though, and just do it as soon as fermentation is nearly finished.
After the diacetyl rest (and the beer is at FG), I rack to secondary. Then, I gradually reduce the temperature until I'm at a lagering temperature.
I pitch fresh yeast when I bottle. I've done it both ways, with and without the additional yeast, and had good results. But, it's taken a long time for some of the lagers to carb up without adding the fresh yeast! I like to boil the priming solution, cool it, and then add 1/4 package of dry yeast to it. Stir well, and then rack the beer into it. It works great, and I haven't noticed any additional sediment.
For lagering time, I've been going with the rule of thumb of one week per every 10 OG points. So, for an OG of 1.070, I lager for 7 weeks. Sometimes a bit more.
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