All (or almost all) colleges require transcripts from every college you’ve attended when you transfer.
Many schools (such as UCR) also use the National Student Clearinghouse to verify course enrollment at colleges.
http://registrar.ucr.edu/registrar/transcripts-grades-and-academic-records/enrollment-verification.html
(See third parties)
Will you be taking upper division courses at UCR?
Some colleges (such as some of the UCs) will not accept transfers if they have a high amount of units.
The answers to your questions will vary by school, so look at the policies of schools you’re thinking of applying to.