There are 3 button states on/with a DVD menu -- unselected, selected, & activated -- & you can set the colorset for each state. By default the #1 set = selected, while #2 = activated. Those 2 sets are by default local [I think DVDA uses the word Custom] while 3 & 4 are global. That means that unless you set 1 &/or 2 to Global, you'll have to set those colors for each menu, which is a good thing if you want to use different colors on different menus. At any rate, the highlight for the selected button is what clues the viewer in to which button they've selected via the remote.

While it's possible to assign a colorset to the inactive/unselected button state, doing so is rare. Colorset 4 is used for subs by default. And you can set the button colorset assignments.

RE: your mouse click sound... Any other sound or visual FX when a button is activated [beyond that button state highlight color] is/has to be done with a video file [normally mpg2/ac3] [regardless the software you use], though you have 3 options on where to put it -- you can have a dummy menu with whatever video or still background & audio track, you can use a separate video file, or you can use a multi-cell menu [i.e. use a loop point] with any FX appearing before the loop point. Buttons can be set to auto-activate when selected, going to another menu or video etc for special FX.

The advantage of keeping FX on menus is they can operate more smoothly with everything being contained within the menu domain [vs. skipping to a short title/video]. Two disadvantages are 1) preparing the DVD can take longer with lower quality results, & 2) menus lag a bit more when they loop to loop points. #1, prepping the DVD, takes longer because unless you delete the default text label for a menu page [plus don't add any visual components in DVDA], DVDA is going to re-encode the menu's background video. You have less control over encoding in DVDA, & it's generally slower than encoding in Vegas. While importing lossless avi for menus would seem a good idea to minimize re-compression quality loss, on a larger or more complicated project I've had DVDA start showing all black frames for every avi video, & that's what it'll render too. :-( I've also had DVDA go bonkers over fps & field order when encoding -- re-purposing a 24 fps BD layout to DVD, in my experience you definitely want to render the re-sized menu video in Vegas.

Far as the lag goes, it's not much work to create a duplicate menu without the intro before the loop point, & have the original menu call it rather than loop itself -- I think you'll find most commercial DVDs take this approach, which can be used for all menus with an intro, or just the main menu where viewers are more likely to have it displayed long enough to loop. In DVDA you re-size the empty image button linking to the 2nd menu to the smallest size possible, *after* making sure it's not included in button navigation, & after moving it out of the way into a corner...Then set the menu End Action to activating that button.

Using a separate video file for FX &/or transitions is easier, & in the project tree on the left of the DVDA window, if you place the video with the menu rather than as or at root level, I think it'll minimize lag by storing the video near the menu on the actual disc. Downsides are 1) IF DVDA is going to re-encode your menus, if/when it doesn't re-encode these short video clips you can have obvious mismatches, & 2) some players, particularly software players, do not like this approach, & you can see glitches, particularly if the video is *really* short. TO avoid the 1st problem, set DVDA to re-encode your transitional video files too in the optimization dialog. TO help avoid the 2nd, lengthen very short video a bit, including some of the before and after frames -- not just the transition itself.

Bear in mind that on a complicated project you can run up against the hard limits of the DVD spec -- for example where you may prefer to store your FX on separate menus, doing so might put you over the limit.