As you set off on this project you should take a look at all the DCC automation devices that already exist. Tony's Trains has a reasonably comprehensive list on their website. I know some professional layout builders are constructing fully automated, computer controlled DCC layouts in HO and N scale. Several layouts have been delivered to customers.
I am an S gauger, many S scale operators use DCC. I considered DCC but decided to use Legacy with the add on LCS (Layout Control System.) It provides iPad touch control but not any automation. In S gauge the Lionel Legacy engines can operate on DCC, unlike in O gauge. One of the major differences in O/S compared to HO is the amperage draw of the engines. This limits the selection of decoders, but high current decoders do exist.
My layout is the same size as yours with 700' of track on four levels, all interconnected. There are eight power districts, each with a 10A supply and about 30 on-off switchable blocks within those 8 power districts. I know some O gaugers use 20A per power district because multiple unit O gauge engines can trip a 10A breaker.
It is nice to be able to combine professional knowledge with a hobby and then build something unique.
