pluggin selection for project

I'm new to Sonar Pro and appreciate the help I've received so far. I've been using Sonar 7 for decades now. I brought an old 7 file into Sonar Pro to take advantage of the plugins. However, my first problem with this 56 track song is when I use this file (32bit) and Omnisphere 2, my PreSonus Audiobox USB crashes and needs to be rebooted. Is this audiobox just not capable of handling Sonar Pro (the original file was written in 24 bit) and when I bring the file into Sonar Pro, the ability to change from 32 to 24 bit is unavailable to me in the audio setup. (I see that when I create a new Sonar Pro file I'm asked what bit I'd like and am offered a full range. Sonar 7 never did this. You went to Options - Audio and selected the bit depth there. Any suggestions here?
 
Also, somewhere I saw that it's possible to scan only the plugins you intend to use in a song file to save CPU, but have been unable to find where to do this. Can I disable some of the 70! plugins in the Plugin Manager and if I do, does it only apply to that song or are they disabled now every time I open Sonar Pro and therefore need to go back to the manager to re-scan the plugins I disabled? Or, is there an easier way so it applies only to the song file I'm working on, not global now?
 
Thanks for taking the time! Much appreciated.