NO Worries! I got ya covered.
I experienced ever issue you spoke about.
The 1415 combo is straight over kill. I went with that set up mainly to keep my temps down as I geared up to a 19t pinion. Where I live near Houston ouside temps get 100-110° for weeks on end. You will love the motor combo you purchased. Tweak the diff. fluid to your liking. Suited to your individual driving style.
Get some metal/aluminum wheel hexs. Ditch the plastic ones period.
Use finishing nails cut to size for the hex pins. Cheaper and will not bend or break. $10 Also the cheaper bearings off amazon have done me right. $10 for 10-20count per size.
Get a cheap amazom 35kg amazon special servo. Set esc to deliver 7.4v if possible. If not its still all good. $25-$30
RX/TX Dumbo x6 / X6FG. $25-$40
Has a gyro do-hicky to boot. Can drive it out of sight and still have signal. Response time is awsome too.
Motor mount link
https://customrcupgrades.com/?s=Mt10
Thats the one and the only one.
Buy with confidence. The above stated items are the cheapest in price but all quality. I own and put every item through its paces. Bash my MT 10 three times a week.