When you select the option to insert the freeze frame into your timeline, it inserts it right where the CTI (playhead) is, splitting all the layers as necessary to do that. (Which is kind of the definition of inserting.)
Before you create a freeze frame, temporarily trim back your soundtrack by dragging the end in so that the song stops before you insert your freeze frame. Then, after the still is inserted, you can un-trim the music again.
The Effects that you mention will have an impact on the number of new frames. The Audio will not be able to follow along, hence the split.
A couple of things that you can do is leave it as you have it, and maybe bring up a music score to fill that time, or Atl-click the Video to separate it from the Audio, add the Effect and not affect the Audio, but you will then have sync issues down the line. Last, but it will take some work, would be to do the latter, then edit the Audio Clip (Alt-click it) and modify the Duration (leaving the Pitch as close to the original, as is possible) in a program like Adobe Audition. Again, this will take some fiddeling to get right and might not sound great.
Personally, I'd opt for the music score to fill the "void."
[Edit] Upon re-reading your post, it appears that the music (your Audio) is linked to the Video, hence it is being altered along with the Video. By unlinking it (Alt-click on Video), the Audio will not be affected. One could also move the Audio (the music) to another Audio Track (Alt-click-drag) so that changes in Duration of the Video do not affect the Audio. I was mistakenly thinking that the music was totally separate from the Video, but it appears that it is not.
If I am now correct, you have Audio and Video of say 1000 frames. You add a Freeze Frame to the Video of say 30 frames (1 sec.) so now you have Video of 1030 frames and Audio is still only 1000 frames. The music would end, before your new Video. Same with a Speed Change in the Video. You will be better off working with each separately, and either choosing new music of the proper duration, or recording a longer passage of the music that you are using.
Couple of things, if you are working on a video track it may be better to add the music after as PE7 exhibits a ripple behaviour, while making changes to one track it can effect other tracks.
The ripple behavior can be overcome by the use of the CTRL button. However it depends on whether you press CTRL before or after you start moving the clip. When moving clips around in the timeline there are 4 basic types of movement Extract, Lift, Insert and Overlay: The first two, lift and extract have to do with how the clip is moved OUT of it's current position. To see what I mean, hover your mouse over a clip in the timeline, then press and release the CTRL key while watching the status text string in the lower left of the application window, you'll see that holding CTRL before clicking and dragging triggers the extract behavior (which tells the timeline that there is a gap being created that should be closed) but clicking and dragging with no CTRL modifier allows the Lift behavior (which tells the TL to ignore the gap) The second two, Insert and Overlay have to do with how the clip is placed IN to it's new position, that is, whether it is Overlaid over exisitng footage without any ripple movement or Inserted within the existing footage, causing any following media (including that on other tracks) to be rippled forward. It is this final behavior that is throwing you because it may affect other tracks in order to keep things in sync after the ripple. Since there is no way to lock down tracks in PE, you must always be mindful of what this default rippling behavior is doing to overlapping media on other tracks.
So basically play around with holding the ctrl button down before or after selecting the clip. You will soon get a hang of it.
thank you all so much for your time and for sharing your knowledge. it is appreciated.