I find it amusing that in the 9 months of "planning and preparation", you only got a bike last week and you still don't know how much the visas and border crossing will run you even though it is all listed on visa websites, and didn't even look up the exact Carnet cost on the Carnet website.
No offense, but at this pace you're going to be planning this trip forever.
The bottom line is that the world is not that difficult to travel. There are pretty good roads everywhere and it's easy to figure out how to get to places once you're in the area. It's much easier than trying to search the Internet for random outdated anecdotal information.
If you run into issues on the road, then you can post to see what alternatives you have...
The best thing to do is to just go.
Your $17K may last you till Nepal and you fly home, or maybe it lasts you till Turkey and you fly home. Or maybe it lasts you till your destination and you fly home. It's going to be awesome no matter how far you get. Not sure what the point is in trying to cover the earth in one giant trip. You have your life ahead of you. You can do more than one trip, you know...
Doing shorter trips - if it ends up being shorter - just gives you a better idea of how you personally like to travel and how much it will cost you and it will help you plan future trips.
Camping is great and all, but it really depends on the region. It sucks being in Paris only to be forced out to some crummy suburban highway campground and not experiencing the nightlife. It sucks going to the supermarket and not trying all the local specialties. Are you really going to pull up to Louvre museum and just admire it from outside to save $15? Because everything is going to cost you money for access. In Africa, you can't even enter most national parks on a motorcycle. And Africa can be very expensive. Want to see the wild gorillas in Uganda? Last I checked, that was about $800 for a few hours. Want to see Victoria Falls during the full moon? That will be $50. All the developing countries know that tourism is big business and all the famous attractions you heard about are usually going to cost something - oftentimes, they will cost a lot.
Which leads me to my last point; Africa may end up being cheaper than Europe and also more interesting. Europe is interesting, but it's basically US with prettier buildings, different languages, and different foods... Trying to keep a strict budget in Europe will make you feel like a bum. In contrast, Africa is probably best done if you camp and it's actually a big positive. It will really enhance your experience. Take the Eastern route and don't feel obligated to circle around every continent. There are no prizes for circling continents.
I do think your route is pretty smart. You're moving from the easiest and safest places and working your way to the hardest and sketchiest (if you do end up riding Africa.)
If you're gonna do it, this is a nice route. It will build up your confidence and travelling smarts.