Originally Posted by NCR757dxr

If you take the ATP written before July 31, 2014, you are grandfathered in under the old ATP requirements and checkride (test is good for 24 calendar months like every other written). No need for a R-ATP checkride; in fact I doubt you will be able to take an R-ATP if you have a valid ATP written from before 8/1/2014. You would have to take the old ride or wait to take the new ATP written to be able to take the R-ATP checkride you speak of.

As Twin Wasp said, the age is 21. Ref: 61.53(b).