I can take a RS file and using CST unpack it into the various files.  I would like to then reload it into EOF and resave it with the RB files options checked.  How do I load the unpacked files back to EOF?

You should be able to create a folder for a project with the unpacked chart audio and Rocksmith XML files, create a project (or use "File>Rocksmith import" and EOF will create a new project) and import each desired Rocksmith arrangement into a separate pro guitar/bass track.  Lots of these arrangements will have dynamic difficulties (each guitar phrase may have different numbers of difficulties), but EOF has Track>Rocksmith functions to flatten the difficulties to make them static.  You can decide whether you wanted to flatten each difficulty and just delete some of the difficulties, or you can flatten the highest difficulty, delete the lower difficulties and manually create the lower 3 static difficulties through typical conventions of simplifying the fully-leveled difficulty.  There will also be some differences in charting mechanics available between the two games so you may have to edit various things.  Let me know if you have any questions.

I have EoF version 1.8RC10

I use CST to unpack the RS file

I create a new project and load the .ogg file  (what conversion bitrate should I select?  256k?)

but Rocksmith Import is grayed out at this point?  ok, so I next change the track to real_guitar

I can now import the RS LEAD track from the arr directory... which seems to work...

I have notes!  Now I save as RB?  do I reset offset to ZERO? 

Often, the arrangement may have only had one difficulty authored so moving that to the Expert difficulty level involves inserting lower difficulty levels in front of it.  You can do this with the "Track>Rocksmith>Insert new difficulty" function and specify to insert a difficulty below the active difficulty.  Assuming only one difficulty was present after import, use the insert new difficulty function three times and then the one imported difficulty will now be the 4th difficulty (like Expert in Rock Band authoring).

 

Optionally, you can then also disable the "Track>Rocksmith>Remove difficulty limit" option to return it from numbered difficulties to named difficulties, but unless authoring certain things that's only a matter of personal preference for Rock Band authoring as it won't affect the export of the notes to MIDI.  One example of where it would matter whether you changed the difficulty limit is if you wanted to use tremolo phrases in the Rock Band chart.  In Rocksmith, this is authored on a per difficulty basis, so if you re-instate the difficulty limit, you would notice EOF would hide any tremolo phrases that were imported from the XML file.  You would have to re-author each phrase by selecting the notes that should go in the phrase and using Note>Tremolo>Mark.

 

If you want to author EMHX, you can use "Edit>Paste From" functions on each lower difficulties to copy the highest difficulty if you want, and make any edits you like to simplify the lower difficulties.  If you're authoring all difficulties, it's usually best to copy from Expert to Hard, simplify, copy Hard to Medium, simplify, copy medium to Easy and simplify that.

 

To reset the offset to zero, you can use the function of that name from the Beat menu.  Usually the option to use equal sized beats (same size as the current first beat) is usually best, but the first beat will often end up being smaller in size to fill up whatever space was left and that may cause its tempo to go outside the range Rock Band likes.  You can play around with selecting a beat and using Beat>Delete to combine two beats into one to work around that, or use the "Beat>Fix tempo for RBN" function to try to automate this process on the whole chart.

 

Then as long as the "Save separate Rock Band files" preference (File>Preferences) is enabled, EOF will create the appropriate files during save.