USB or Squeezebox Touch from Mac to DAC

Folks,

My first question on Audiogon - so hoping to get useful responses!!

My Setup:

Mac (Runinng Squeezebox server) - All FLAC files!
Squeezebox Touch
Peachtree Nova (as DAC only)
Nait-5i reciever
Harbeth C7 Speakers

The dealer where I brought my speakers told me that I could signifcantly improve my sound by getting rid of Squeezebox and using USB directly from my Mac to the Nova.

Q:

a) Is that true?
b) My Mac is in another room - so will have to be a veeeery long USB. Does that still work?
c) How do I control the music (remote) if I use USB?

Thanks in advance...

Raj