If I've registered my TurboTax cd-rom and loan it to someone else to use when I'm finished, will the other person be able to access any of my personal information?

No, they will not be able to see your personal information; it's not stored on the TurboTax CD.

No.  When you use the CD/download your tax file is stored only on your own hard drive or any backup device you use like a flash drive; it is not stored online.  However, the license code is for you to use on computers that YOU own, so loaning it out is not okay under the terms of service.