your second point was a huge sticking point for me ahahah there used to be orange arrows that appeared from the stations. but after a little while with 10+ stations it got real messy so I decided to make it based on the objects that actually exist in game.
honestly a radial menu like in sims would probably be best. Click on cat->click on station->radial menu appears(input, work, output)->then the cat does what you ask of it.
if you hit 'output' you then select another station and hit 'input'
thank you for the kind words! <3