The problem with cheerios, or at least the main one is that they have added iron which is bad news for most birds. When people say that they are good for them they are just thinking that they are oats and oats are good. You could make some old fashioned oats for him.
It is a bit harder to live with a fully flighted bird but it is also a good measure of how well your relationship is doing from the birds perspective for they same reason that you are asking about clipping. If the bird doesn't want to be with you it can just fly away from you. A bird that bonds to you and trusts you is very likely to want to spend most of its out of cage time on you. Also because flight is such an integral part of being a bird it is hardwired into nearly all of the birds major systems and flying is one of the most healthy things for them to do. The ability to fly affects how their brain functions and how well they learn to solve problems, the ability to fly also affects them emotionally as well as physically. It affects every major system in their body directly or indirectly and unless there is an actual medical reason for clipping a bird I do not recommend doing it. Personally, I have not found any problem that can't be solved by other means.





