You can scrub, you do it from dragging the red line at the bottom of the timeline. Press scroll lock if you want to hear audio scrub at the same time.
I dont think smartsound is in liquid so your prob best to use studio do get the music.
The deinterlacing sounds like a setting in the export settings of studio. I dont no much about studio 9 but this would be my guess!
Im not sure if your aware that you can import projects from studio into liquid. Go to file then input wizard.
Hope this helps.
Full Specs: 3.2 Pentium 4 Processor, 1Gb RAM 80Gb Root Drive, 120Gb Video Drive + another 160Gb external, Adobe Premiere Pro, Pinnacle liquid edition pro, ati radion 256mb