fall

Do not capitalize the season when writing about semesters.

He is taking a lighter load for the spring semester than he had during the fall.

The cadet plans to take 12 hours of classes during fall 2014.

freshman

Do not capitalize terms pertaining to class years unless part of a formal name.

Freshman Convocation

Sophomore Leadership Seminar

Plural: freshmen.

Note that “freshman” is singular when used as an adjective.

The freshman orientation was well attended.

[Tip: if unsure, replace with another class as a test. You would not write “the seniors class trip” so do not write “the freshmen class trip.”]