Our kids (4 1/2yr old twins) play along with an adult and enjoy putting the trains on the board. And sorting the train cards by color. But they are too young to play by themselves. But it is a great game tho!
The box says 8 and up, and I completely agree. The average eight year old who enjoys challenging games would be perfectly capable of doing well playing this game. But don't let that fool you -- my husband and I have played countless times with intelligent adults who absolutely love the game, too! It can be a challenge, depending on how deep your 'strategizing' goes.
I use the game for kids aged 6 to 10. For the 6 year olds I simplify the rules a bit. The 10 year olds can handle the full game.
I would say you can use it for almost any age range, provided you are flexible with the rules.
I am not too familiar with color blindness but there is a site you can Google which rates Board Game Information for the Color-Blind written by a person who is color-blind. They rate "Ticket to Ride" as Fair saying some of the cards and routes might prove difficult. The game was rated "fair" not "bad" as other games were. I think it is up to the individual to decide. Sorry i could not help more.
I would think so, but it depends on how young. The game pieces are pretty small so not younger than 5. I would also co-play with an other child or adult the first couple of times. That would assist in getting the concept of route completion. My students LOVE this game and they are 10-12 years old.