Regardless of if you decide to do a required or an elective class, only take one class. Summer session is so condensed compared to a regular quarter, and as an incoming freshman you presumably don’t have experience with how fast-paced a regular quarter is to begin with. Don’t overwhelm yourself, especially not before your freshman year has officially started. If you take summer sessions later on you can decide whether you can handle an additional class or not.
As for whether to take a GE or a required class, that’s largely a judgment call. Would you rather get a GE that you may not really want to take otherwise done so you don’t have to worry about it later? Or would you rather knock out a prereq so that you’re slightly ahead during the school year? There’s no right or wrong answer here, just personal preferences.
For what it’s worth, I took CHE 2C last summer and actually liked the pacing a bit better compared to CHE 2A and 2B during the regular school year. I don’t know how 2A is run during the summer though.