Re: reliability is a must!
All of the above is good advice.
Here's something else to keep in mind. It's a motorized bicycle built by you with your talents and skills. It is not a motocycle that was designed and built by engineers in a factory. You must determine where the potential for something to fail is and design/buid to eliminate those things.
You can gain a lot of input from the members here but my advice would be to build it right following advice you see here but then ride the bike for a while to 'work out the bugs' before relying on it as your daily transportation; if that is your goal. Proper break in of the engine as well as the rest of the build, bearings, brakes, chains and sprockets, is essential.
As with any machine your bike will require periodic maintenance to keep it running properly. Treat it right and it will return the favor.
Age and Treachery Will Always Triumph
Over Youth and Skill & "Charlie Don't Ride"