@Jason Wu
There are several considerations that can go into the analysis of whether you need an LLC or whether a large insurance policy will suffice. As you say, a DST is another option. Your decision will depend on several factors like the type of property, type of tenants, your risk tolerance, other assets you own, your estate planning, laws where the property is located, etc.
Any lawsuits would be limited to the assets of the LLC and not your personal assets (assuming you run the LLC appropriately and the corporate veil is not pierced). But, an LLC will not limit you from liability in total. You can still lose your investment in the LLC. If you're going the umbrella insurance route, make sure it will cover you for several things including just the routine slip and fall (like mold or earthquake). You'll also want to ensure you have a good property manager to look after the upkeep of the property if you are not there to notice anything deteriorating or which may need attention.
Creating an LLC in California would cost you a minimum tax of $800 every year. You would have ongoing filing requirements with the State and would need to keep business records and documentation. If you create an LLC, you will need a business account. California does not recognize series LLCs so each individual LLC would cost you $800 in California.
You also want to look at whether a pass-through entity helps your bottom line and your taxes. There is a new 20% pass through deduction you may qualify for that could help you, but not everyone qualifies. You should still be able to get this even if the properties are not in an LLC if you qualify, but you will want to ensure the DST does qualify you for the deduction.
With regard to getting your name on title, you will want to talk to an estate planning or real estate attorney about this. If you want your name on the deed then you will need to discuss such things as how to hold title and whether it causes other issues such as property tax reassessment. There's other questions as well about whether you made a gift to your partner when you gave him the money and then whether it would be a gift back, or whether you documented the loan and your interest in the property and whatnot. If you're going to hold title jointly and not in an entity, you may want to consider something like a tenants in common agreement that governs your rights as owners and who can transfer or sell or encumber the property and who is liable for the mortgage, etc.
Also, if you do not have an estate plan yet, you will likely want to get your living trust completed and other ancillary documents such as a Will and power of attorney, etc. In California, probate is a huge hassle and decedents are subject to probate at pretty low dollar values that having a family trust once you own property is almost essential for planning and peace of mind.
These are all things you will want to discuss with your attorney and CPA. If you need references for either of them in San Diego, let me know.
*This post does not create an attorney-client or CPA-Client relationship. The information contained in this post is not to be relied upon. Readers should seek professional advice.