Leaking hot water shut-off valve
I replaced my kitchen sink this past weekend and when I shut off the water with the shut off valves (the oval handle twist kind) under the kitchen sink the cold water shut off completely but the hot water was still running. It wasn't a regular flow like normal but a pretty decent flow so what I did was was shut off the water main and the hot water flow definitely was much less but still a small trickle stream that filled a gallon ice cream bucket about every 20 to 30 minutes (not exact on the time). Basically I detached the line from the sink handle area and laid the link in bucket straight down.
Do I need to replace the hot water valve or was the problem the hot water heater was still "pushing" water? If I do replace it do I shut down the water heater (electric) and drain it partially or open the sinks downstairs?
The valve is a threaded kind so I think it would come off with a crescent wrench easily but the way the water was draining while replacing the faucet I don't think I can get the valve replaced without too much water flowing everywhere.
I was hoping for some direction on safely getting the water stop flowing before attempting something like this.
Also just a side question. I used plumbers putty on the rubber seal that goes under the deck plate. I put a small bead between the seal and the metal sink. The seal doesn't sit perfectly flush all the way around so some of the putty is "exposed". Is it dangerous or toxic as a wash cloth gets it wet and it moves around the sink? I mean its not a lot but just a small amount I might be worrying too much here.
Also the same think the plumbers tape. When I wrapped the threads on the new lines they had some in the pipe so to speak. Is that toxic as water runs through/over it or does it wear down and clear out after a while?
Sorry for the questions and thank you for any help and advice in advance.
Brian.