Haven't cleared VC1, as it is much more annoying.
1. Yes, girl interview parts have to be completed in order. The very first girl on the menu's interview is impossible to pass until you have completed some of the others first. Hint, the girl's on the first 3DO release are the first girls you can pass with.
2. The game doesn't tell you how many points you need to clear each video, making it a lot more guess work and frustrating then VC2.
3. Unlike VC2 which had a bigger budget and hired actual pr0n stars. VC1 were actually just random girls they picked up off the street, and you can really see the quality difference.
Due to the more frustrating gameplay, fugly faces, lack of extra unlockables, and no 3D support, VC1 really feels more like a prototype that gets annoying quickly. VC2 is actually fun, and the one I recommend to all LA owners.