I have just hooked up my first lager to gas last night. 2 weeks fermenting at 50* and 5 weeks lagering at 40* but was only a 1.045 beer. I fermented in a 10G round cooler I use to mash with and was able to hold the temp within 2 degrees the whole time.
I know the temp was in the range in your garage but how did you get it to not fluctuate more than a few degrees from morning to night?
1. Lager is done after fermentation and is the defining element of a lager, clearing a beer up, leaving it very crisp.
2. A fridge would be good for lagering and if you can lower the temp a few degrees until you get to about 10* less than you fermented at.
3. don't bottle now, wait until you have lagered for a while, lagering times vary, but 6 weeks is a good guess unless you have a big beer but doesn't look too big based on that recipe.
4. After bottling you want to move them to room temperature to carbonate for a few weeks.
I am just a begginer at Lagers, so someone else might come by and give better advise, but this is what I know from my first one.