I have the water flowing into only 1 lift tube... then again, I have
just one solid plate across the bottom of the tank. If your UGF
consists of two separate plates, then it would probably be best to use
a T connector to run separate lines to both individual plates.

The air stones shouldn't pose a problem, however they may interfere a
bit if you're to run a heavily planted tank... if you are not planning
on a heavily-planted tank, then this would work just fine for you as
far as aeration. There are quite a few plants that can also tolerate
the extra current and lower CO2 levels.

We were all new to this at one time... take your time, experiment...
trial and error will give you more insight. It's still a learning
process for me and I've been at this since age 12.