I plan to replace most of my temp RF sensors with wired ones. I would like to do this bus

The orange part is optional... i would like to do it (freezer & fridge sensors) but they may get things too complcated?
So the bus has a lenght of 14,1m and a weight of 22.9m (optional version) or 18.9m (short version). I also plan to use 3 wires (not a parasite setup)
My three questions:
1- What wire size should be best for this? (I can get nearly all type of cable for free at work, so if there is something better than network cable...)


2- Is there formula or else to calculate the good size of the resistors (& capactiors?) and where it should be best to put them?
3- Is there a test that i can do with an oscilloscope to test my setup to be sure to get things working nicely?
thank you guys for your help and sorry for my english
Nicolas