Re: New to all of this
If you're getting 28MPH on a brand new build, you're fine. Ride it a couple hundred miles, and it'll get a little better.
Reinforce the fenders where the tabs and arms meet the actual fenders, or they'll vibrate apart and wreck you badly.
For front brakes, you can add a caliper brake (inexpensive), or a vbrake bracket and vbrakes (a little more expensive), or a drum brake (either laced into that rim with new spokes, or you can get a whole wheel from Husky for about $100).