you can do wifi tether, it just uses an adhoc network at the moment. We are all waiting for a true hotspot outside of the VZ app. I have a corporate laptop, I would love to be able to use my DX to get some things done while on the train home.
corporate IT groups like to block the ad-hoc networks as wifi options for security reasons. It is those same security reasons that also remove the options of usb and bluetooth tethering... so infrastructure mode is the only way for those devices. For your own personal device, ad-hoc is just fine, though you may have to push a button now and again to reconnect since windows wants to make sure you really want to connect to them.
I upgraded from the envy 2 so I know what you mean. Service will depend on your location. I am in the Twin cities in Minnesota and get great service. As long as your pulling 3g, your doing great. Only minor delay compared to my wifi at home which is g so 54Mb.