Thanks for the guidance everyone. I really appreciate the input. I found a
local SCORE office, so I'll be getting in touch with them shortly to
understand the steps I need to take.

You may want to contact a good business attorney and perhaps an accountant.
As Corporate Attorney mentioned, when you deal with other people's money,
there are numerous regulations with which you will need to comply, including
consumer protection ones as well as financial ones. You might also begin by
contacting your state department of finance. Their answers to your questions
may determine the viability of the idea before you get too deeply involved.

Hi, In addition to what Corporate Attorney said, you might consider  getting in touch with a local Small Business Development Center or SCORE, two of SBA's resource partners. They're located across the country and provide free business counseling and answers. Visit our local assistance guide to find your local SBA resource partners by entering your zip code.  

Sounds good. Thanks for your comment. I'm in California as well, and am
looking into everything it takes before I officially push the GO button. I
have the domain, concept, website wireframe, marketing plan, and the logo
currently being designed. I think I need to stop beating around the bush and
just go for it. Just want to make sure I cover all my bases.

It really depends. Forming a company here in California can be done for a few
hundred bucks, but if you'll be an online business you'll have fees related
to equipment or leases (for example). One of the most expensive and difficult
issues I'd flag for you is that whenever I've had clients whose businesses
have them being the middleman for people's money, as could be the case in
your business, there are a ton financial, privacy, etc. regulations that must
be complied with, which then increase the legal fees.