Installation Questions: From X1 to X3 (with a pit stop at X2)

1) Just leave it there.
2) Just install all of it (or just what you want) Sonar will do the rest. Don't worry about what is already there.
3) Just install X3. You can separately install any missing plugins from X2 later via custom install.
4) Yes assuming you are on the latest versions.
5) Just install X3e followed by reset, then a rescan of your plugins. Ideally do not run X3 until you've installed X3E.
6) Assuming you won't need to reinstall windows all will be fine.

7) I also strongly recommend you run windows update several times and also review the optional updates (easier to do this first). Oh and don't forget to back up before and afterwards. Also now might be a time to make sure your firmware and drivers are up to date.

Dimension Pro has been at version 1.5 for several Sonar releases now, and if you have it installed already you do not need to install it again - it has not changed.
 
The same is true for Rapture, which is at version 1.2.2, I believe.
 
As far as incremental maintenance, once you do your initial X3 install, you can then apply X3e directly after that, as X3e is a 'cumulative' update, meaning that it contains all of the updates from the earlier maintenance releases as well.  So, X3e has all the fixes from X3a, b, c, and d, as well as e).
 
The rationale behind leaving prior installations installed is that some things, like V-Vocal, were dropped, so if you have any older projects that contain V-Vocal clips, you would have some issues due to V-Vocal no longer being present.
 
V-Vocal was part of the X1/X2 installation, so the entire X1 or X2 base installation would need to be retained, to be able to preserve V-Vocal for use in X3.  Melodyne has replaced V-Vocal, but does have differences, so many folks just keep X2 around to be able to open things with V-Vocal, and also in case they want to use V-Vocal in new projects, instead of Melodyne.
 
There are some other things that had been dropped as well, but I cannot at the moment recall what they are - perhaps R-Mix?
 
Oh, Perfect Space and Session Drummer 3 are also the same in X3 as they were in X2 (and maybe even the same as from X1), so you would not have to install those again either, if they are already present on your system.
 
The actual installed footprint of the basic X1 or X2 products is pretty small, and they won't get in the way of anything else.
 
I guess the last consideration that comes to mind is that, for whatever reason, if you have issues with loading any projects in X3, that had been created in X1/X2, then having X1/X2 remain present might give you an additional safety net.  Things are supposed to be backwardly compatible, and there certainly are not bunches of posted complaints about it in the forum, but it is just a peace of mind thing, in case.
 
I hope I haven't further confused you.  :)
 
Perhaps others have additional thoughts on the whole thing.  I LOVE X3e, and hope you find it as stable and powerful as I have.  :)
 
The way I have always approached moving to a new full release of Sonar is that any projects that I had already started with the older version, I complete in the older version.  New projects would get started in the newer version.  It is NOT required that anybody approach it like this - it was just a choice I made, so that I would have no particular worries about anything changing detrimentally from having a project that spanned multiple versions of Sonar.  (This is just offered as an explanation of how I do things, not as something you have to do)
 
Bob Bone
 

V-Vocal is part of the X2 install, which is why you need X2 in order to have V-Vocal on your system, but once it is there, it is indeed accessible to projects in X3.
 
Lots of folks keep X2 installed for retaining access to V-Vocal in X3, even though you get the basic version of Melodyne with X3.
 
I don't know if they are still doing it or not, but when X3 first came out, once you installed it, you would get notification of a special upgrade price from the Melodyne folks, to get 50% knocked off the cost of upgrading to the top of the line version of Melodyne - which is WELL worth grabbing.  The special price upgrade offer was good for 30 days, and if it is still in effect, I believe it was $150 to upgrade, rather than the normal $300 cost.
 
I hope I have cleared things up for you - X3 is my favorite release of Sonar since time began, and is quite stable AND has a lot to offer.
 
Bob Bone