Low temperature shouldn't be a problem once it installed. If the putty is cold when you install it you might want to warm it in a bowl of hot water.
I would suggest plumbers nylon thread sealer tape instead.
This product is used to install sink drains in metal or fiber sinks. It does not harden and relies on compression between two surfaces to form a water tight seal. It has no caulk or glue like properties. You have to compress it between two surfaces to get a watertight seal.
Nope, this would not seal a crack under any form of pressure. You would be better off with something like Flex Tape.
Yes, it will work well for the drain and/or fixture mounting.
no it is meant to be compressed and used for a sink drain. it has no uv properties whatsoever. best bet would be a GE silicone all purpose caulk like GE 012A
Yes you can use this product on stainless steel or any other metal surface to seal a drain.
No, not even.
No. Plumbers putty is mainly used as a seal between drains and sinks/tubs. It is not meant for that.
No, replace the toilet.