Thanks to Darrel Taylor's response at techsupport assitant at meLabs, I have solved this mysterious problem. Let me explain, because this may be encountered by other users of the Micro Code Studio Plus (MCS+) ICD.

It turns out that the ICD model that came on my CD-ROM that delivered MCS+ to me was not correct for the 18F4550. Darrel had downloaded this .inc file from the Beta models and emailed it to me. When I replaced the ICD model I had for the 18F4550 with the one he sent I started seeing Variables Tab.
The icons I thought I was missing in the tool bar only show when using a boot loader, as explained by Bruce Rentron in above post.
Chasing down this problem took 3 days out of my time....no thanks to Mecanique's tech support who never responded to my emailed request for support.