Clone to smaller SSD drive?

[bill from maine]

Dave,

You replied on one minute!
Thank you!

I have to admit that I have not paid careful attention to sandboxes because I never understood them.
So I just read the manual on this !

You say that the Sandbox - shared users and applications "doesn't copy your user data or applications."
I presume that this is not the best choice, because I want applications on the SSD drive too - for speed.

On the other hand, Sandbox - Shared users "shares your user data between the two volumes, but makes a copy of everything else, including your applications."

Assuming that I use the SSD for my Sandbox, am I correct that this will copy everything EXCEPT the user folder to the SSD drive?

I just ran the program WhatSize (as an Admin user) to see what the sizes are of the various folders at the root level of my primary drive.

Not counting the User folder, I found out that my (root) Library, Applications, System, private folders are the biggest and total about 76 GB.
The remaining large folders (usr, .Spotlight, bin, sbin etc total about 1.5 GB

Given that the remaining files and folders at the root level are very small, am I safe in assuming that a 120 GB SSD drive is plenty big enough?

If I then run the computer off of the SSD, do I install new applications to the SSD drive?