Well, there's not much to it. While moving from 7 to 8 was so awkward we had to decide if it was worth it, moving from 8 to 9 is so simple it's hardly worth writing down. The only extra step is to import the Work Environment.
You should be able to simply open your 8.1 project in AC9. You should be able to open your PM 3.1 layout book in PM9. If you don't change the name of the project file, the views should update in PM without fanfare.
That said, I wouldn't make the jump the day before the construction set is due. Use common sense.
Just in case, put a copy of the project in your Old Files folder with a modified name. Don't change the name of the working version of the file. If you do, you'll have to relink in PM.
Libraries: Switch your libraries so the following are loaded:
• From the carrot, within Master Library 9, '1 Rill & Decker LIB9' and '2 Project LIB9'.
• 'Archicad Library 9' from your local Applications : Graphisoft : Archicad 9 : Archicad Library 9. (We load the Archicad Library locally because it's faster and it never changes, so there's so synchronization issue.)
Stop using the Master Library 8 entirely. If you are working with a AC7 project that has been brought forward, continue to use the 7 library as you have been.
On the subject of the cache library, there are intermittent issues with it. If it works for you, use it. If not, don't. If you have weirdly missing parts, this is the first thing to check.
For the new Master Library 9, I copied the whole Master Library 8 to start, and I have been updating and replacing some parts along the way. As version 8 parts get superseded, I move them to the 'xOld Objects' folder. This folder loads, so you can keep using the placed parts indefinitely. For new placements, you should use the newer objects in the normal folders. To remind you, the 'xOld Objects' folder is a jumbled mess, making it very hard to find anything. Don't try.
If you have missing or misbehaving Library Parts, it's probably a change that was made in the 8 library that didn't get copied to the 9 library. You should immediately let me know of any issues so we can dispatch them right away.