I can help with some of this, but not the dithering. I've changed sample rate from 48>44.1, so I'll describe my process when doing that. Also not exactly sure when you say "trim" your tracks.
Preparing file for tracking:
1. Change sample rate in lower left hand corner of the gui where it says "Project rate:". Just select 44100.
2. Select File > Export as wav.
Someone else will have to verify this thought, but IIRC if you mark tracks at a higher sample rate, track timing gets messed up when you burn then try to downsample to 44.1.
File tracking, using the new wav you just exported:
1. To mark a track, select Project > Add Label At Selection. There's a short cut for Mac: command b
2. Apply fades, etc.
3. Hint 1: if you need to cut out anything between tracks you've already marked, make sure when you select the piece of wav to cut that you highlight the area all the way down into the track marker indicator bar. If not, when you make the cut all subsequent track markers are now off line from where you put them. Also, "undo" is your friend.
4. Hint 2: when you export the tracks, the first track will start with your first track mark, and not at the beginning of the wav file in which you're marking tracks. So where you want the first track to start, make sure you make a first track mark. You'll see below that the end of the file is a different story, and I'm not sure if this is consistent with other software.
5. Hint 3: Duh, I know, but save very frequently as you go. I find Audacity will freeze or crash with greater regularity than anyone would ever hope, and has done that through several iterations.
To export the tracks:
1. Select File > Export Multiple...
2. In the pop up box, select wav as export format
3. In the pop up box, select/create folder where you want those files to go
4. In the pop up box, under "Name files" on the lower right of the box, select the radio button for Numbering consecutively
5. In the pop up box, optional: alter file name prefix
6. Finally, and still in the pop up box, click Export button
7. All tracks will export as wav files, and when done, click OK
8. Hint 1: if you wish, delete the final track. All it is the the remnants of the show after you've made the final track mark after the last tune/applause.
Then open TLH to fix sbe's and run 'em through.
edit: clarified a few points