You probably already realize this: One spigot has a 'hard' gasket or washer for the pour-in hole on top - it's shinier. The other spigot has a 'softer' gasket that better seals the lower pour-out hole on the side - and it is dull in appearance. If they are switched - easy to do - the lower spigot will leak. Perhaps take a look at the difference: The duller, softer, washer belongs on the lower-side as the out-flow spigot.
I havent done any work for the last two years ( heart attack etc) but when I did I use the combi tank in a three tank set up The combi held the developer and the other two tanks ( being Rubber Made containers found in the local grocery store.) the stop bath and fix. The combi film holder fits nicely inside, They are clear plastic and have to be use in the dark , one for stop bath or water and the other for Fix. Dip and dunk works fine for the developer and if you want to use the developing tank in the light you can always put lid and agitate the whole tank
. At the end of the cycle turn off the lights and transfer the rack to the stop bath and then the fix for the required 2 to3 minutes and turn on the lights and use the stop bath tank for washing .The combi tanks use about 43 oz of developer as I remember ( I could be wrong about that) and replenishing the developer is possible as opposed to one shots .