For cables, take a look at BlueJeansCable. I’m sure there are much cheaper options, that are pretty good too. However there is little value in spending more - unless you like the look of it. People obsess about cable lengths, etc. I think for interconnects, 3-4 feet is a good balance of flexibility and length. With 6 ft and below, there should be no audible noise/signal loss with decent cables.
The sys has no active electronics. Also RCA/line level cables have very low voltage/current, so there is little to no risk of short circuits etc. that can cause damage.
yes, you will need to get off the couch and press a button to switch sources. A remote controlled preamp or integrated with HT Bypass would have the advantage of the remote.
I don’t know what you mean by arrows. RCA cables should be bi directional. If your cable has arrows in them, there are a few possibilities.
1. The cable has has a chip (voltage booster?) in it. For short distances, this is not needed. Probably needed at 20 ft or more where it might make a difference. Better to go balanced at that distance.
2. Some cables have chips to alter the sound. I would stay away from those
3. They painted an arrow on it to charge you more.