1) SoCal will probably start much higher than 150k, but it might be worth looking into. Find someone familiar with that market, as I am in Georgia, not California, and can only tell you what my associates in SoCal are saying; get it from the horse's mouth.
2) There's no such thing as "minimum down payment." What you put down will depend on many factors, such as: a) the buyer's prerogative b) your credit picture c) the property d) the bank's prerogative.
3) Form relationships with REALTORS in the areas of interest and they will be able to guide you better, once they have more details of your situation.
4) Mortgage rate is a question for lenders (ask many, not just a few), not real estate agents. Avoid agents who attempt to speak outside their area of expertise!
5) Same goes for taxes; consult tax professionals
6) Property management companies: look for referrals. You need to be very cautious about the management company you choose. Some charge too much. Some do too little for you. Some charge too much AND do too little for you. The only way to know is to have experience with them. If you want to save yourself heartache and personal experience foibles, ask others! Get referrals and investigate thoroughly!
7) no matter what you do, you need to be cautious and knowledgeable; it's not easy and it's not safe, but it can be profitable if you're willing to put in the effort and proceed prudently!