An IRA is qualified vehicle allowing you to invest for retirement in tax-deferred environment. As long as you invest passively - income and gains inside of an IRA would be sheltered from taxes. An exception would be when you use leverage to invest which would result in UBIT tax. It will however not have any effect on your personal real estate investments, since it is separate entity from you personally.
Ive been looking into doing this also and know enough to be dangerous. I have really been struggeling to find someone whose knowledgable on this and can help me guide me on the process. Any financial guys I call will not help because in my opinion they do not want to see the money moved out of the ira.