The TVs will need to have discrete power and input commands. This means the TV has an ON and an OFF instead of the typical POWER command and you have INPUT 1, INPUT 2 etc instead of the typical INPUT command. Luckily most name brand TVs have this capability but obviously you should check before buying. You can do that by posting here with "Does the Samsung Model X have discrete commands?" and someone here will probably know.

The Cable boxes are usually a crap shoot. Some will have discrete power commands some wont. I normally just leave them powered on if they dont have an OFF command.

"as well as controlling many other items such as cameras, intercoms, doors, etc.."

Your post title talks about TVs and then you mention cable boxes...which i assumed was a given with the TVs but now you are talking about other items. Do you already have a plan for these other items and you just need an audio video control solution? Or should your post title be "I need a PC based control system for multiple items like TVs cable boxes cameras intercoms etc"?

If you are looking to control all those things and you are "lost here" i would strongly suggest you just hire someone who can do this for you.