Empty apartments are hard to come by in Santa Ana. Expect your search to take a while, although you may of course get lucky and find a place within weeks of starting. In reality though, your search will likely take a couple of months, even if you start in prime season between May and July.
Your financials will be the most important part of your application in Santa Ana. Because of the high costs of rent, landlords know that there are many people who will be unable to meet their payments. You need to prove somehow, through a combination of income verification and credit scores that you're capable of paying for an apartment before a landlord will rent one to you.
As throughout the rest of Orange County, the OCTA transit system provides some basic public transportation in Santa Ana. There is also a trolley line that traverses the downtown at the start of the week. However, a car is the best way to get around Santa Ana if you have long distance or regular commutes.
If you like to shop, hit the MainPlace Mall for all of the standard mall stores. For a good meal and live music, Original Mike's is the place to go. Santa Ana is not right on the beach, but you can get to the beaches in other Orange Country cities in only a few minutes. Then you can truly enjoy the best of what SoCal has to offer.