I have managed to make a semi automatic brewing stand by taking and using a couple of hoppers to load water bottles automatically from a chest and load reagents. The tricky part is the reagents. You need to load them in order from left to right or you can hose a potion.
I can set it and come back to a set of potions (sometimes four or five steps) without too much effort.
H CC | | BS - H
BS= Brewing stand
I tried auto unloading but it just cycles the water bottles, sadly.