Yes, these are correct. I have never read the original account, so cannot help with diet section.
Yes, they would have eaten veg. and fruits when available, please keep in mind that people have believed for generations that they would die without them. Apparently not much, though.
I doubt if they ate any raw meat, someone correct me if wrong, prejudice against that has always been very strong, and note the "nine pounds of meat per day" - this is only possible with cooked meat. IMHO
I've read and studied the Lewis and Clark Journals quite extensively. There are several important points to keep in mind. First, the year 1804 hardly qualifies as being squarely in the Paleolithic period. We had already gone well beyond Paleolithic, through Mesolithic, and into Neolithic. Also, almost all tribes were already trading with "the whiteman", and were well on their way to adopting European customs. They also had very sophisticated tools and weapons, as well as fully domesticated animals which is far removed from what little we know about their Paleo ancestors.
The accounts of killing and eating bison while traveling through the Great Plains area states that the Expedition would make a kill, butcher the animal, and then roast it over an open fire. While the explorers were waiting for the meat to cook, the Native Americans would eat the cast-off organ meats and offal raw.
As for the large consumption of food by the Expedition members, remember that these explorers were doing incredible physical labor. They were rowing against the river current all day long, and often porting the boats and supplies around rapids and falls that could not be directly negotiated. There are few people in our modern world that come anywhere near close to this kind of energy expenditure day, after day, after day, for months on end. Probably the closest we come is something like the Tour de France bicycle race, and even then I'm not sure it's fully comparable. Yes, there are some intense sports, but they are very short term - usually hours in duration and certainly not weeks or months.
There are accounts of tribes, not in the Great Plains area, migrating long distances in the spring and summer to kill and preserve animal meat to be taken back to their home area. Also accounts of the Natives eating selective roots and some plants during the winter months to avoid total starvation.
Very fascinating and well worth reading, but the bottom line is that this is an account of explorers of European decent, encountering modern Hunter Gatherers with rather sophisticated technologies compared to what true paleo man would have had. Even so, it is pretty clear that even at this late date the preferred diet of Native Americans was meat based and plant foods were used mainly for survival when the meat ran out. Also, it was the explorers that cooked their meat, not the Natives.
Lex