Q1: If I have a modem, will I be able to use this service?
Service can be attained through a modem, but at a minimum, a 56K connection is required. At lower connection speeds it will be sluggish but it will still work.

Q2: How come I see area's of my virtual desktop blacked out? The reason for this is that your color map settings for your monitor or at 256 colors. To correct this set your color map settings to 16 bit and then re-login to your virtual desktop.