No, it is NOT a legal requirement that you record a preliminary notice. It will not affect the validity of the preliminary notice if you don't record it. The advantage to recording a preliminary notice is that the Recorder's Office is supposed to send a copy of the Notice of Completion to everyone who records a preliminary notice when the job is over. The Notice of Completion starts the clock ticking for mechanic's lien and stop notice and payment bond rights. However, some counties are better than others at sending these out and you are still bound to follow the same time limitations even if they don't send it to you. You don't often find Notices of Completion on private residential jobs. They're more often found on public jobs. The bottom line is that the vast majority of preliminary notices are NOT recorded.
You do not need to record the preliminary notice.
This answer does not constitue legal advice, nor does it creat an attorney/client relationship. If you are seeking legal advice upon which you intend to rely, you should hire competent cousel familiar with this area of the law in your locale.
No you do not need to record the 20-day per lien notice, but it must be served on the owner and general contractor by certified mail, as your lien rights arise based on the date it was properly served.
This is NOT legal advice, just a general discussion of the law, as we are not familiar with the specific documents and facts of your case, etc. Please consult with a competent attorney in this area of the law for specific legal advice regarding your particular case, as the advice may vary depending on the facts.