Hi Belli,
Motor size estimates are likely in the ball park. I have similar size lawn tractor at 48V. I don't mow with it. The current for moderate speed, like you'd do for mowing is around 10 amps.
For the blade motor, that is a tough one to estimate. I think maybe you should go larger. 2kW continuous rated might hack it, but the blade can really load down with a patch of tall wet grass. Like when it stalls a 12 hp gas engine
Mowers and small tractors are great "getting started" EV projects. There have been a few on this board. I think there should be a sub-forum for such EVs, like "Tractors, Mowers, Non-Road Worthy and Weird Stuff". Hey Woodsmith, how about it
major