I read in a thread here that you can never not be increasing your speed. i.e. you can't keep your speed constant. Is that true?

 

kind of yes, the brap brap idle is the engine misfiring. it does this because there is too much exhaust gas that gets into the intake with the throttle closed.
if you set it up just right, it'll just be really touchy, but it'll continue to buck and snort at part throttle.

when you can open the throttle though that problem goes away and it makes a bunch of power

so the engine kind of trains you to be either accelerating a little or decelerating a little instead of just going a constant speed, if its a daily driver it gets kind of annoying, but a weekend car probably not

 

Depends. I have a full peripheral port and I can cruise at anything about 3k RPM. I've also spent ALOT of time tuning on the street for drivability though. Large port motors can definitely be tricky to drive, but it's certainly possible.

 

i should also add that if you have a heavier flywheel it helps smooth things out