Hi Adrian,
for security reasons, two persons have to walk in front of the tractor (technically one at every wheel) and often our mayor walks and greets people visiting the parades. Politicans ...
Yes, I have to pay taxes. There a two models in Germany: Historic vehicles (>30years and a certificate from our technical control (TÜV)) can pay 191 Euros (except motorcycles, they are cheaper) or you pay by emission class (cars up to 3,5t) or weight (trucks, tractors etc.).
I pay 236 Euros for 4 tons max. weight. If you are farmer (and have actually a running farm) you get a green numberplate and are tax free.
But if you do non-farming transports (e.g. furniture for a move) it is tax evasion.
I have no farm, so I pay per weight.
Insurance depends on purpose: If you do no work with your tractor and drive only to shows (and parades) you pay ca. 30 Euros. If you want to plough (even in matches) or do some work in a forest or any normal work, which the tractor did in his first life, you have to pay more.
If you are free of accidents for some years, you get a rebate (and loose it if you crash). Actually I pay 130 Euros (including three years of rebate) insurance, but I'm allowed to do normal work with my tractor.
It seems possible to get a state of historical cultural Shark to get tax free without beeing farmer, but it again limits the use of the tractor.
There is a round sticker on my number plate. It shows, that this vehicle is registered, paying taxes and insurance. If you don't pay one of them, authorities remove this sticker. You are not allowed to park on public ground (streets, parking lots etc.) without this sticker. Driving around without sticker is strictly forbidden.
Peter