Mine smokes (unburned fuel) on start up also...all diesels do. GEB had a problem that was extreme, and is worth mentioning. I increased my glow cycle by 10 seconds and the problem went away....there is quite a bit on this board, if you research this topic.
I,m not an expert, I've gpot 25 hours more on a tractor than you, but I'm a fast study. Having the rear tires filled with something is critical if you are going to use the FEL. Its a counterweight, helps with traction also
. Rim seal is a commercial fluid made from beets, environmentally safe if you get a leak. Some fellas use calcium chloride or windshield washer fluid to fill their tires. One caveat, if you're using soemthing that will promote rust, have the tires tubed and the tubes filled with your product of choice. Bottom line, ask your dealer, that's who'll fill them for you.
Basically their are Ag tires and R-4's. Ag tires are skinny and have an arrow design. They are suppose give you more traction in mud. R-4's are much wider lending to more stability, they may offer less traction because they have a much less aggressive tread design. This is by design so they dont screw up your lawn etc. They are thicker and tougher and are reported to take more abuse, less chance of a puncture.
The century has an option which cocnsists of rear hydraulic connections and a towing plug...its a nice option I didnlt thinkI'd need but I did end up using it...glad I got it.
This board is full of good folks, very willing to help and spend your $$. Some of the guys who chime in are dealers and they can be a terrific resource.
Good Luck.....ram