Hi there everyone. You would not believe my excitement when I found this website.
My husband and I were houssitting for my folks when we found a green IRN.
Upon taking him to the vet, we have since found out that he is +/- 3 months old, his tail feathers and his nails/claws need to be clipped as well as the food the pet shop sold us is dangerous.
As you can see we have a lot to learn and are eager to do so.
Is there anything else to be done or that he needs?
ps:he is very particular about who he shows affection to...
I'm not sure if I understood your post correctly but you did not mean to CLIP the tail feathers right??? You get the wing feathers clipped...so they have limited flying. 
The tail feathers shouldn't be clipped at all!
If you decide to groom your bird (clip his nails, feathers) on your own make sure you get tips from your vet so you do not cause any injury to your new little bird.
As far as food goes fresh fruits and veggies are great along with a seed mix sunflower seeds etc. just make sure you NEVER give him AVACADO or CHOCOLATE as it could cause death! 
Hope this helps! 