1) I don't see any other option for you. However, you don't need to do a formal post-bacc program. Since you've already completed some of your med school pre-reqs, you can enroll in the rest of your required coursework as non-degree seeking student at any 4 year college. Or you can enroll in a formal post-bacc for career changers. Getting into med school is never a "sure thing" no matter what the post-bacc program director will tell you (especially in CA!). Please don't go into debt for post-bacc!
2) Most career changer post-baccs so not require a GRE.
3) AMCAS has a searchable database of post-bacc programs here: https://services.aamc.org/postbac/
No recommendations. Sorry.
4) Your age may be an issue for med school admission, but since you'll be a year or more older by the time you complete the rest of your pre-reqs that should take care of itself. Your lack of physician shadowing, community service and research experience will be a bigger issue.
And a word---you are a world away from choosing a medical specialty. Please don't fixate on neurosurgery. Concentrate on the first step--that is completing your pre-reqs and strengthening your CV so you can get accepted into med school.