Whew. Good read, here, too!
I had read the same thing, SadiesMom, that a raw diet can lead to slightly elevated BUN levels, and is nothing to worry about. Whether the numbers you're seeing are 'slight' or not, I have no clue. Glad to hear you're going to see a holistic vet, hopefully they'll have some insights and suggestions.
As for fruits and veggies - since Sadie has bad reactions to some, that tells me right there that she doesn't need them (those particular ones anyway) - her system rejects them. Since you've made the link between sugar and diarrhea, you're ahead of the game there!
Denna will eat anything, so she does get lots of fruit and veggies. I've read that they digest better if they're well ground/blended (Denna gets my juicer pulp), cooked, or previously frozen, all of which help break down cell walls before the dog's system sees them. Of course, that a food needs some sort of pre-processing to be made bio-available to the dog, pretty much tells me it's not what their system was designed to run on...
But, I've also read studies (via Dr. Mercola's site, I think), that suggest dogs on a raw diet with added fruits and veggies do have lower instances of some diseases. Not sure if it's a statistically significant number... but, since I have left-over juicer pulp, and Denna likes it... I'll share!
Good luck understanding all the lab results! Glad we have Ruth and others here to help with it all!