Terminology ... "track" refers to a physical screen space that stretches horizontally across the entire project. You have 3 or 4 video tracks on top and 3 or 4 audio tracks below those. The items you put inside those tracks are not "tracks".

The items you drag onto the screen that contain audio, video, and text are called "events". We'll be able to communicate a lot better when we all use the same words. :)

1) & 2) Seem like severe system problems, not related to Vegas. Not that we don't want to help; we really do, but the answer lies outside of Vegas so it's gonna take a lot of diagnosing. Do you have similar problems in other programs?

3) Are all the headers of all the tracks highlighted? Press Shift-Ctrl-A to deselect everything first. This may show you that all tracks were selected. Now clicking on a single event should highlight only that one thing.

4) As pointed out above, i believe you're trying to merge two events, not to tracks. Vegas doesn't have this function, nor is it generally needed. With appropriate use of auto-ripple generally the events will never separate unless you deliberately choose to separate them. If you wish you can highlight both and press G to group them. This doesn't help much because any future grouping/ungrouping will override it, but psychologically you might feel good about it. Trust me though, merging isn't really necessary.

5) The help pages contain a wealth of information. Check out Keyboard Shortcuts / General Editing. You can move events left & right on the timeline 1 frame with the numeric keypad 1 & 3 keys or 1 pixel with the 4 & 6 keys. I don't see anything for specifying a time duration, but the duration of 4 & 6 will change depending on how far you are zoomed in. If you're zoomed out to see an entire 1 hour project o the screen then 4 & 6 will nudge maybe 30 seconds. If you're zoomed in far enough to see each individual frame then they can nudge in millisecond increments, assuming you have Quantize to Frames turned off.