from #1 to #3 just i dunno but on #4.. maybe late 1900's, and others just dunno... hefuly theres 9+10 or many will be confused if it is 19 or 21.. stupid 21..
bcuz the wheels spins too fast, i see the limit it will be stable is 800 rpm. slow down the rpm, if you need mor speed, i recommend to add some thrusters hope this help you