How long to walk from Beihai hotel to Jade Sreen cable? Are there guides and porter on Huangshan?

You may need walk an hour to an hour and a half. There are porters, but no guides.
The trail is not hard to walk, but if you take bit luggage, it may be hard.
If you want to go downhill as well as seeing the beautiful scenery, you can choose to walk to Yungu Cable Station (Could Valley Station) and then take the cable car to go down.