Inserting a clip into another clip without throwing off audio timing

Hello new and learning a lot...
I have several clips setup with audio matching at good points.
I need to insert clips here and there and text without throwing off
the existing audio timings? If that makes sense...Im thinking key mark and the razor tool
for this but Im still learning what everything does?

You can edit them in using Overwrite "D" drag them in using Position "P" or edit them in as connected clips "Q"

Hope that helps.

in addendum to Seanus excellent suggestions how to accomplish a CutAway:

BEFORE applying a clip, shift-2 switches to 'apply video only'.
after doing so, don't forget to switch back, shift-1 ...

.. in case, you haven't known that yet ......

Thanks and theres a lot I don't know about this yet haha

Another possibility is to detach the audio. Then you can do whatever you like with the video, like cut in other clips, and your audio will remain untouched and editable as you need.

Thanks
The problem is the video and audio are sync'd at a perfect spot in several areas...so I dont want to throw off the audio in part of the clip while I insert the new or adjust image/video into the existing clip
Does that make sense?

Yes you can use the trim tool to do this. But if it was me I'd just edit on as a connected clip then lower it down into the primary storyline when I'm happy with its position. COMMAND-OPTION DOWN ARROW When in Position mode. If you do this while audio is expanded it won't overwrite it.

Thanks Seanus that sounds more like what I am wanting to do.