If you can press Q, you can play Hecarim. The most 'difficult' thing on Hecarim is to not screw up his E - if you're ganking you want to run past the enemy first then knock them back into your allies but tbh even that's a minor detail and doesn't really matter.
I wouldn't focus too much about his MS scaling either, it's cool but it's not really an essential mechanic. Just build 'normal' stuff and take Ghost and you'll be all set.
Hecarim's 'style' is to use his insane speed and giant ult distance to pull off ganks and engages that most junglers couldn't do. It also allows him to be a really annoying chaser/split-pusher along with all the other implied benefits of running really fast and doing tons of damage.