Your local bike shop is the place to shop and get questions answered.
I'd recommend you get an entry level road bike, about 54 cm. Ride it until something breaks, probably a spoke. Or, maybe nothing.
In other words, don't modify anything until you have to.
Because of your weight, you may have to replace the rims with stronger models. May not. Just wait and see.
Tires. Again don't switch 'til you find you need to. Then go to a puncture resistent Schwable, Continental, or Vittoria. Just make sure it's got a kevlar or similar belt.