About how much weight would I lose walking 5 miles a day in a month?
2.5 of the walk is uphill and 2.5 is downhill if that matters.
You can only find out yourself, it sounds like a good plan why not try it. It's not like you'll have any negative side effect from exercising mildly haha.
Diet is 75% of weight loss, focus on what you eat & you should shed 4kg a month at least.
Depends how many calories you eat. You have to burn more than you eat to loose weight.