The DigitaLiza opening is a little bigger than the film frame so you get a bit of the edge mask in the scans and just a tiny bit of the edge numbers. The frustrating part is that because the opening is a little bigger than normal holders, it grips less of the edges of the film strip. If the film isn't pretty flat, it can be quite a trick to get everything lined up and snapped shut with the whole film edge gripped cleanly. That said, once it's in there cleanly, you can keep the un-cut strip in the holder and gently slip it through like a conveyor belt to center each set of photos.
Re: dust: 1. I use a Swiffer and DustOff can to clean the area where I'll be loading up the film. 2. I pull the whole film strip through a film-specific anti-static cloth a few times. 3. Once the film is in the holder, I use a film-specific anti-static brush to loosen up anything that may have gotten on there while wrangling the film into the holder. 4. Just before starting to actually scan, I blow off both sides of the film with either a Rocket Blower, or (gently) with a DustOff can. This routine keeps things pretty clean.