If something happens to me, will my wife automatically get the house I bought before we got married?

In California, a house you bought and paid for before marriage is considered your separate property, although it is possible a portion of it may gradually become community property over time. Without a Will, your wife will get half the house and your sister will get the other half (assuming your parents are deceased). With a Will, you can dictate who gets the whole thing. Plus you designate who you want to be in charge, called the Executor, which is usually the same person as stands to receive the bulk of the estate. With a Trust (one step up from a Will), it is possible to have your estate handled after your death without the need to go to court, if that is a concern, but a Trust is not suitable for all situations. See an estate planning attorney.

Yes, you have several options. You should have a consultation with a lawyer who works in the estate planning field.

Yes, your wife would get the house if it is in California. Without a Will, she is your immediate heir.

As next of kin she should get the house through intestate succession, but that is a costly and time consuming process. Set up a trust and put your home in it with your wife as beneficiary.

Yes; suggest you see a trust estate planning lawyer to protect you from probate court.