It is about a 2-hour air journey from Beijing to Hangzhou. You can find the details of this flight through China flight schedule on the web https://www.travelchinaguide.com/china-flights/ .
Weather at the end of March is cool and pleasant in Hangzhou. The average temperature may be about 12~14C.
Friendship Hotel Hangzhou is a nice 4-star hotel at the West Lake Scenic Area of Hangzhou. It costs about $72 to $214 per night.