I am a frugal e-biker, except I have more than four, so a real frugal person might think I'm nuts. My personal interest is small light geared moors in the rear wheel. I rarely go over 18 mph either.
If your ebike has pedal assist, you probably need brake cut-offs to do low speed maneuvers, unless you are willing to shut down the power. I believe the Leeds has a pushbutton on/off throttle only, so that's how you can get away without brake cutoffs. Whether cutoffs are good in a panic situation is up for discussion. I haven't tried to time how fast a motor can shut off when releasing the throttle, but with pedal assist, I estimate there's at least a half second of lag. Comments I've seen from trail riders say they need brake cut-offs. Given how often I have stabbed the brake pedal in my car with my left foot while my other foot still has gas pedal depressed, I believe them.
The e-brakes sold for most ebike kits are cheap, especially when you look at the flimsy cable adjusters. They do sell sensors you can place inline with a brake cable that work. I've not used one. If I ever need one, I'll take the magnetic switch and magnet out of a e-brake lever ($5-10) and epoxy it to a good lever.
I've looked at the install manual for the Luna geared offering, and believe it doesn't support pedal assist. If you want a powerful motor that is throttle only, it's an option. I suppose it's a habit, but I prefer to pedal as much as I can in the lower assist modes. If I was a commuter, maybe I'm on the throttle all day until I get to work. Anyway, the Luna motor is a big motor that can pull 30 mph, which I don't need. And yes, plenty of riders have throttle only and like that. I wouldn't.
I've laced a couple of wheels. Started with a fatbike rim. Mediocre results. The next two were thin rims. Much easier. It's probably worth $100 to buy it assembled, or a little more to have it done at a bike shop. You probably don't get the better spokes on wheels assembled in China.
Never had a front wheel motor, unless I count the one in my 2WD fatbike. I don't know if I'd like an 18 pound wheel assembly on a regular bike, but I don't really feel it on the fat bike, which balloons to 75 pounds with the extra motor/battery in the winter. If you go with the Luna 750W motor up front, I think it comes with one torque arm. Buy a second one. Those are aluminum forks, no?.