I have found learning mine, that once it is at desired temp. just small adjustments to the ball valve is all I've needed to do. These things are pretty basic as far as burning goes. I made sure my coal basket is on legs 3" high and my intake pipes are at 2" above the bottom of the barrel and the air flows right up under the middle of my fire just fine.
If it is a matter of not wanting to bend over (it can be hard for me with my back some days, not just lazy) you may consider putting riser pipe on all of your intakes and use valves on all (cost permitting mine cost $9.97 plus tax) of them I have thought about doing this on mine, I find myself loosening one or 2 caps instead of removing them when the valve is full open to bump the temp up. Also, you may install valves without the risers with the handle pointing away from the drum in the open position and use your foot to open and close them which would give you ultimate control at each intake.
If you are using 4 intake pipes, I think the 1/2" pipes give PLENTY of air flow.
As far as loosing the caps, I don't worry, the caps I bought for my 1/2" pipes were $.99 each.
Keep in mind I'm only starting out with mine too, so take what I say with a grain of salt.
PS with the wind I have been smoking in, it is almost impossible to get an even 360 intake, perhaps your idea may remedy that, can you post a sketch of what your trying to do? My simple mind can't quite grasp how you were wanting to connect all 4 vents to a single valve.