B1/B2 Tax Report Questions

I got married in last Summer when my wife visited here with B1/B2 visa. After that she came couple times with B1/B2 visa. However, her total staying days are less than 180.

For this situation, what should I do with the tax report? On the tax report, my marital status should be married, right? Then from married file jointly and married file seperated, which one should I choose? My wife didn't have income in USA. For married file jointly, should I report my wife's income in China? For married file seperated, should my wife file a report?

Thanks for advice!