You may have already decided on these questions. If not, I have a question - what do you mean "drain to the A/C unit upstairs"? Hopefully, you're not planning on "recovering" the condensed water from the AC for use in your tank. While the water condensing out of the air is pure, once it goes through the AC, it's contaminated with dust and bacteria, and perhaps more importantly, potentially contaminated with aluminum and/or copper and lead from the condensing coils.
With respect to your question about pushing water from your laundry room to the tank controlled by the ATO, that can be done with litermeter pumps or the Apex DOS pumps, but not the pump that comes with the Tunze Universal Osmolator. That pump is just a small centrifugal water pump that can't pump against more than about 5' of back pressure. You can, however, buy an auxillary outlet for the Tunze that allows you to connect any AC powered pump to use instead of the supplied one, so you can use a litermeter auxillary pump, for example, to push RODI against 50 feet or so of head pressure. To make that work, you'd need to locate the litermeter in the laundry room, then run a 14 gauge wire or extension cord from your laundry to your tank, and plug it into the Tunze auxillary outlet.
The other alternative that you mention is using the RODI's water pressure to push purified water to your tank. While that can be done, most would advise against connecting an infinite supply of RODI to your tank's ATO. There's just too much risk of equipment failure that would flood your house and kill your critters.
If you still want to go this route, BRS made a very useful video discussing connecting RODI to your ATO
here.