After all the years of brewing Cold Crashing is one the steps I myself think is one of the better steps.
I cold crash all my beers when in secondary, temps I would say mid 30 range.
Just try one for at least a week and mid 30's and you will see the amount of sediment in bottom that you would have been putting into your bottles or keg's.
The length of time I would say its up you yourself. I have a Christmas beer I brew in early part of year and it is cold storage until Dec. before is kegged.
wonder what the freezing point of beer is..... and I guess it would have been better to figure that out a couple months ago, when it was only cold rather than freezing...
Colder is better for crashing. You can go down to 30 if you want. If you're going to fine or filter the beer, it's definitely better to get it as low as possible.
i usually just cold crash at whatever my garage fridge happens to be at (around 40 i'd guess) for a few days, i might turn the dial down one to get it a little colder, but i normally only go a few days before kegging it.