You can def fit an outside tap to the hot water supply if you wanted.
I'm a window cleaner and I know quite a few houses where I top up my water, where they've got both hot and cold taps outside ........
I could never understand people having a cold tap outside with a hose to rinse the car off....and walking through the house to fill up the hot wash bucket.
Yes you can. I often fit 'mixer' taps on the outside of properties, allowing temperature control for the dogs, cars & motorbikes...that we can't live without! Make sure you put a non-return valve on each pipe though!