Briefly:
Filing as married filing jointly is always allowed as long as both spouses agree, even if you have different incomes or one spouse is non-working. Joint filing almost always results in lower overall tax or a higher refund.
As far as your business is concerned, I assume you have already been filing business taxes so nothing really changes. If you are a single member LLC or a sole proprietorship, you file a schedule C like usual. The schedule C for the business income and expenses, and schedule SE for self-employment taxes, only have your name on them and only apply to you, even though the net profit flows to a joint return.
However, if your spouse materially participates in the business, that needs to be recognized. There are several ways to that, if you need further information, post a followup with more details.
