Almost everyone you will talk to about the college ap process has very passionate opinions - many are simply wrong - sometimes even me. As you go through this process - you need to validate everything with people who KNOW the correct answers. They typically work in your target school’s admissions office. You are getting a bum steer about having the option to apply freshman vs transfer - @mikemac is correct, i encourage you to contact a UC and ask. They have heard it before and won’t laugh at what you think may be trivial questions.
Your point about cost savings is valid and - whether you go in as a freshman or Jr, it won’t matter - transference courses will be on your transcript and count toward your graduation… . almost no matter where you earn your degree. Some charter schools are different but, I know neither of my kids could have handled 11 units at a CC in addition to their regular HS coursework. Other than sanity (which isn’t a joke, I know lots of stressed out kids on meds to control anxiety due in no small part to an absurd workload) Your risk is having your GPA drop if you overload - and that will undermine your shot at the school you want to attend , not to mention merit aid. You are a LOT more appealing applicant to most colleges with a 4.0 in relatively easy courses than a 3.0 in really hard ones. It is a balance you need to find.
Your comment about Evergreen State leads me to believe you may not be a CA resident. If that’s true, UCs and CSUs are probably not your best option - especially if your finances are constrained. Our state charges an absurd sum for OOS tuition and is really stingy with aid to OOS applicants. Most OOS students find privates like LMU and USD to be more generous with aid.
On the EC front - While the CSUs really don’t factor them in - While GPA centric,UCs want to see applicants with some out of classroom experience and ideally leadership - a job, sport, music, club, theater are all ways to demonstrate that.
It varies a little by campus but, this is a good overview of the 14 things they consider.
http://admission.universityofcalifornia.edu/counselors/files/comprehensive_review_facts.pdf
I sincerely encourage you to find ways outside the classroom to demonstrate your awesomeness. From the way you write, and comport yourself, I am confident you’ll find some pretty easily if you look. I’d also add - I am pretty confident you’ll find your way to a college that’s right for you - even with a bum steer now and then.
Good luck.