You need to have 30 hours to be considered a sophomore. If you don't have 30, you are still a freshman. Some schools won't let you apply as a transfer student until you reach sophomore standing. If UIUC is like UIC, you can't apply as a transfer student until you have 26 hours at time of application. If you don't have those hours, you apply like a freshman applicant.
UIUC does give second priority to UIC students.
The credits will transfer. The issue is the number of hours. The credit hours might vary between the campuses.
If you have completed UIC's LAS foreign language requirement, you should not worry about UIUC. UIC's LAS requirement is actually one of the strictest in the entire University of Illinois system because you still have to take the placement exam even if you took 4 years of high school language.