No problems. I'm a Major. I think that I am the third-oldest guy in my Squadron (140 officers and men), but I don't really worry about it. I feel it after sports, but that is my own fault for trying to skate like a 21 year old.
My advice for you is to apply for the branch that appeals to you and just go for it. Blaze forward at full speed and see what happens. I have had colleagues transfer to other branches at varying stages of their careers (some voluntarily, some not so voluntarily) and it seems to work out. I can't think of anyone going EME, but there are plenty of other interesting branches out there if you find yourself wanting a change at 35.
My plans is to be an officer in armour or artillery for as long as I can.
I realize when I`m older I wont be able to do the stuff I was able to do before, so I`ll just pace my self.
Then IF I can't take it I will switch to EME or something.
Do you have any info on switching?
Can they deney your switching of occupation?
For the life of me, I can't find any info.