The walk is fine if it's a nice day. Basically cross the road (Park Lane) and follow Serpentine Walk long the north of the lake. You should come out at Lancaster Gate and Paddington is a short walk. Get the concierge to give you a map. It should take about 25 minutes. In answer to your questions:
Yes - it is a nice walk if it is sunny
I would certainly have no problem with doing this. Even at 6 there should be a few people out and about. Having said that London is a large city with the associated nutters etc etc...
There was a large concert/festival this weekend that may affect the walk
I walk from Hyde Park Corner to about 2/3rd the way up Park Lane most mornings.