1. Of course. But I think 20 minutes you also don’t have to call. And sometimes you think you are close because you don’t know the area so you don’t know you will be so late.
2. Many people are noheig not to shave, and only trim for halachic reasons. Probably that is why.
3. If you borrow a car, you can’t always ask for it to be perfectly clean. Maybe the shadchan should supply the car if he cares so much.
4. Give me a break. Just how many hours would you like him to put in before the date–keeping in mind he probably doesn’t have internet. Maybe he should drive to all the places the day before. This is how life works; when you drive to new places you get lost.
5. This is not common at all, and the fact you include it among your general advice kind of detracts from the rest of your advice.