I don't know if #1 is accurate, but #2 and #3 are definately not correct.
To disable NAV, just right click on the icon in the tray and select Disable. You can even easilly configure it to not start up automatically when you boot so that it's available all the time. Unlike most virus programs, it not only scans all your incoming mail, it also scans your outgoing mail.
You were also incorrect about #3. You get a one year subscription to the virus definitions, then you pay to renew the subscription after that. A $10 or so outlay once a year is definately not the same as having to repurchase the program. Plus, if you don't resubscribe, it still keeps working fine, it just doesn't get the brand new virus defs.
Trend reviews poorly next to NAV, I'm curious how recent your experience has been with these two products. NAV is Editors Choice, handily beating the competition.