>>>I have been trying to "scrub" in the way I used to do with SpeedRazor or *argh* Premiere.

after using P for years that was the hardest thing to get used to in Vegas. don't worry though it doesn't take too long :)

Two ways to scrub in Vegas:
1 - you can grab the scrubbing thingy (yellow... down at the bottom of the track header)
2 - you can hold CTRL and click-n-drag the cursor on the timeline. but it doesn't drag like in Premiere, you control the speed by moving the mouse left or right.

VV4 has a much higher limit to the scrubbing rate.