Yes, it's possible to earn an ICSP while a college programmer freshman or sophomore. Sounds like your son is a 2nd semester sophomore at this time- the first year he was HSSP covered so not being considered for ICSP I assume, and now he's a college programmer who is moving on to field training and advanced training this summer/ next year?
No, he does not specifically have to apply for the ICSP - he will be considered.
Really he should be getting these details directly from his unit and chain of command - I'm hoping he knows this but you as the parent just have some questions (I'm a parent too and that is always fine) - just make sure your son takes the lead in understanding his options and the timing of notifications.
Not everyone on scholarship or a college programmer in AFROTC gets selected to move forward after the first two years, so congrats to your son on that. I just don't know how often ISCPs are awarded when they are in the same window rejecting some on scholarship from moving to field training. Let us know what you find out if it might help others. Good luck.