For red just look at matpats video
Why blue has one of his eyes missing is because during a show with his riends he suddenly went rogue and attempted to attack his first friend.The security attempted to stop him eventually having to take an eye out,his eye being lost also explains why he canon see the player with the box
For green before the entire rogue incident red experimented with the rainbow friends in one experiment one of the chemicals affected greens eye causing him to be blind.To make up for greens lost eye,red gave him better touch/hearing so he can tell apart humans
For orange in one of the experiments he was given a serum that made him react differently with food ,due to this though he would hunt any creature that had food and often had to be fed several times
For purple before he could be experimented on he quickly got into the vents to avoid red because he knew better than any of the others.he adapted his eyes to see in the dark to make up with the lack of light,although he couldnt stay in the vent forever.this lead to the leaks in the vent. He was hunting for food.
Now,what was reds device in chapter 1 ,well it could be to power up the machine to create the rainbow friends, after all this place was abandoned,and i doubt they payed the bills
But enough is enough now i think when yellow and pink get introduced will be reds newest rainbow friends,he intercepted the bus thus causing him to get more subjects.after all odd world is nearby so lots of buses are probably coming which mean more vic-i mean "volunteers"
In chapter 2 i predict one of us ,just like the pther rainbow friends were injected and as we escape we have a secret rainbow friend.
But hey thats just a theory,A GAME THEORY!!!AAAAAANDDD CUT!
