Just a quick note as regards Musical Timebase vs Linear Timbase (and, hopefully, all will become clear )…
Let’s say you have a very simple 8-bar MIDI Part… it contains just two quarter-notes, the first at bar #1, beat #1, and the 2nd one at bar #3, beat #1. The tempo is 120 BPM, so the first note starts at 00 secs and ends at 00.5 secs, while the 2nd note starts at 04 secs and ends at 04.5 secs.
Now, with the MIDI Track in Musical Timebase, we change the Tempo to 240 BPM.
“Musical Timebase” means that the notes (and their lengths) stay tied to their Bar positions, so now the first note still starts at 00 secs, of course, but now it ends at 00.25 secs (i.e. it now plays twice as fast/lasts half as long). Similarly, the 2nd quarter-note remains fixed at Bar #3, beat #1, but Bar #3, beat #1 now occurs at 02 secs and that note now ends at 02.25 secs (so the two notes now play twice as fast).
Let’s put the Tempo back to to 120 BPM, and compare that with what happens in Linear Timebase…
“Linear Timebase” means that the notes (and their lengths) stay tied to their Time positions, so…
when we change the Tempo to 240 BPM, the notes, and their lengths, do not change at all (because, fixed in time, they remain at 00 secs till 00.5 secs and 04 secs till 04.5 secs, respectively. But… at 240 BPM, 04 secs is now where the start of bar #5 occurs, and 04.5 secs is the end of bar #5, beat #2 (or, if you prefer, the start of Bar #5, beat #3)… so those (ex) quarter-note have now become minims (half-notes)!.. but, because the tempo is now twice as fast, those notes sound exactly the same as when they were quarter-notes at 120 BPM.
So, that is how we can use this method to change the look in the Score, without changing the way it sounds.
As regards the “regular” Logical Editor, which handles only MIDI events, yes, it can move the starts and ends of (MIDI) notes, but not automation, nor tempo events.
The Tempo Track Editor (maybe already in SX3, I can’t remember now) has the function “Process Tempo” which can multiply/divide the values of the tempo events, but cannot scale their positions (while the Project Logical Editor, in later version of Cubase, can only do the contrary , but it can scale the positions of Automation events, and also trim their values. )