You'll need to cut an equal amount off both sides of each door. Otherwise the doors may bind in the track since one will be wider than the other and they won't open completely. If these consist of 4-12 panels, basically you'll be taking 1/8 (about a saw blade width) off of each side of all 4 doors. Easy enough on a table saw...would be a real PITA with a circular saw. Bypass doors would be much easier.

The windows are Pella (double pane, 10yrs old, new construction windows); insulation, R13 is in the walls (1/2in drywall on both sides); no doors w/ gaps. From what Pella tells me, the windows have an STC of 28; and the walls are 39 I read - both I guess are poor? I was thinking of adding soundproof windows to the existing windows to improve the STC; and add green glue and 1/2in drywall to the walls as well. I just don't know if I should do one first over the other. Any advice?? And where would I get soundproof windows??