I want to review my old college applications via FERPA - is this possible?
Can people [request their records under FERPA] for schools to which they were not accepted?

No. From the FERPA text, education records are defined as:

those records that are:
(1) Directly related to a student; and
(2) Maintained by an educational agency or institution or by a party acting for the agency or institution.

and a student is defined as:

any individual who is or has been in attendance at an educational agency or institution and regarding whom the agency or institution maintains education records.

Since you have never been in attendance at the schools who rejected you, you have are a not considered their student and FERPA does not accord you any protections.
This accords with most &quot;plain English&quot; descriptions. For example, it agrees with this description from PrepScholar and this explanation from USC.
As Nate points out in the comments: &quot;section 99.5 (c)...says you don't even have the right to view your application records if you applied to a different component of an institution you were already attending.&quot; So there is no loophole if you applied to grad school at your undergraduate institution.
There is therefore no question of &quot;choosing not to honor the law&quot; -- rather, the law does not impose any obligations on the school until a student-university relationship is formed.

What is the retention period? I would think that if I applied over four years ago, they might not have my record on file...?

FERPA does not specify any retention period. As noted here, however, state law may impose certain retention requirements.
In a larger sense, the goal of FERPA is protect privacy and allow students to correct errors in their educational record. It is not concerned with the admissions process directly (until the point where admissions documents become part of the student's educational record).
I agree with the commenters suggesting that you would do better to ask professors you know to review your application materials and give you feedback. I admit I am also a little concerned that you are still seeking &quot;closure&quot; five years later, but that is perhaps a separate matter.