Interesting tickets. Well the law is the law, and I think most places its 500W and some provinces/states allow for more wattage. Engines are 50cc's and a certain speed limit of 30kmh. This brings us to the next situation. Did they seize your ride at the time of writing you these tickets? To inspect the "vehicle", the serial numbers and the capacities (watts/cc's and speed) If no, they didnt seize your ride, then thats good - in your favor. If yes, they did seize your ride then thats is very bad.
So the license plate (no tags) thing might stick. In which case if you need a license plate you would also need registration with a personal automobile license of a certain class and perhaps even insurance. So then that might lead to a no insurance ticket, which in my province is a $2750 fine or 44 days in jail and they give you a year to pay, the second no insurance fine within a year the fine amount is at the judges discretion. Its not unheard of for a $10,000 no insurance fine for a second offence within the same year. Thats in Alberta Canada.
Stop sign, might stick. But its the judges discretion to throw it out, or reduce the $$$$
Peddles, you can get away with because I doubt the cop that wrote that ticket is a licensed automobile inspector, if that sticks they need a real safety automobile safety inspector to come in. Hence what I mentioned earlier about them siezing your ride.
Anyway, I would only suggest you get a lawyer, heck even a paralegal (traffic) lawyer might work to get the lowest amount of fines possible and a few thrown out. Come up with a good "story"
These tickets might even represent demerits points. I really dont know.