Just got 6-year old cockatiel - help!

Question
We just rescued a 6-year old cockatiel, probably male, from some people who couldn't keep him any longer.  He appears healthy, has a large comfortable cage, and has been on an all seed diet.  Iunderstand that he should not have gravel(not needed because cockatiels crack their seeds before eating).  We put in a cuttlebone, and he likes it, but throws it back up almost immediately.  I take it the cuttlebone is not digestable.  Does he need another calcium supplement? He is all white and gray, no other color at all.  Is that unusual in a male bird?  How long do cockatiels live?  We put a carrot in his cage today, but he doesn't seem much interested yet.  Should we encourage him to eat vegetables and fruit?  Thanks for any input.

Answer
Hello Neena and thank you for your post.
Congratulations on your new friend!  I am sure that you will find a lot of joy with him.
It sounds like you have a White Faced Grey Cockatiel, and while they are not as common as the Regular Grey, they're not that uncommon.
It sounds like you've done some homework (Kudos to you!).  You do understand correctly.  He does not need grit.  It won't hurt him if you gave it to him, but it's not a necessary thing for him to have.
Cockatiels do hull their seeds, which makes the seeds easier to break down in the Cockatiel's digestive system).  
As for the cuttlebone, they are great for Parakeets/Budgies, Finches, Canaries, etc., but anything bigger does seem to have a problem digesting them (with the exception of my guinea pig...lol).  You can get a larger calcium block from your local pet shop.  I buy the extra large calcium blocks for my Cockatiels, I have one Cockatiel that will go through a whole one in two weeks when she is laying eggs.  I have never had a problem with any of my birds throwing them back up.  Also, an all seed diet is not good for any bird.  Seeds are high in fat, and this can be hard on the bird's liver and kidneys.  Slowly try to get him on to a pelleted diet, which in the long run is even cheaper for you too because there is actually less waste.
I know Cockatiels that are over 20 years old, but their lifespan is usually around 15-17 years old.
Try giving him some cooked carrots to start with (he might try soft vegetables at first).  Fresh carrots may scare him at first, but yes, definitely encourage him to eat fresh fruits and vegetables.  Also, try giving him sme apple chunks, banana slices, dandelion greens, kale, romaine lettuce, a little bit of cooked corn, a piece of orange, things along those lines.  He'll probably go for the banana, cooked corn, or the apple right away.

Please come back if you have any more questions.

Good luck and God Bless.
Dianna