Can I be sued by owner of patent-pending invention?

Dear Rich: Say there is a known prior art that currently has a patent pending and I file for a provisional stating claims with which I believe are the non-obvious to the prior art:

• Can they accuse me of infringement and take me to court?
• Can I sell during my provisional status and if or when do I have to stop selling because there is a known prior art with a patent pending status?
• If this invention which I believe is non-obvious to the prior art shows that it has commercial value, but there's a known prior art - Is it worth filing a non-provisional after 8-12 months?
• If my invention is non-obvious to the prior art will a patent be issued and do I still have to license the basic idea of the prior art?
• I read in your book that changing something small may be considered as a novelty and may be considered patentable (if I am correct) - If so, do you have to go to court to prove that or can the examiner just approve it and when a patent is issued to the non-obvious then you are protected?

Gee, that's a lot of questions and we've only got 20% of our battery power left on our Mac. We better get busy! We liked your use of bullet points so we'll respond accordingly.

• No, the owner of a patent-pending application cannot sue you for patent infringement. The owner of a patent-pending application cannot sue you for patent infringement until (and if) the patent issues. If the USPTO doesn't grant the patent, there can be no patent infringement. If the USPTO does grant the patent, the owner can only sue you for infringements that occur after the patent is granted with one exception. 18 months after the regular patent application is filed, the application is usually made public. If the applicant notifies infringers after that 18-month publication that they are infringing then -- and only after the patent issues -- can the patent owner sue for infringements that occurred between the date of notification and the date the patent is granted. We previously explained these principles here.
• You can sell your products after your provisional patent application is filed but ... keep in mind that selling triggers the one year on sale bar, and also that if you are infringing a soon-to-be issued patent, you are likely to be forced to stop. As you may know, your provisional patent application does not grant you any rights. It merely holds your place in line at the USPTO for a year until (and if) you file and successfully pursue a regular patent application. And for that to all work, the regular patent application must reflect what's in the provisional patent application.
• Is it worth filing a provisional patent application? We don't know. You need an attorney's advice or perhaps you can find it pursuing this guide we posted online.
• Will you have to license rights if an examiner determines your invention is novel and nonobvious? Probably not but there's no guarantee that the examiner got it right. A patent holder can later go after you and challenge the USPTO findings.
• Does changing something small get you off the hook if the examiner approves the application? Same answer as above.

Wow, looks like we made it before our Mac shutdown. Thanks Mr. Jobs!