Hmmm... Changing the popup link text is a tricky one, because it's embedded down deep in CG-Amazon.php (and if you ever wanted an update to CG-Amazon, you'd lose any such minor mods...). Lemme think if there's any easy way that I could roll into a next version, where you wouldn't have to hack up the code.
As for the second Q: not much if all you want is a text link. A raw CGA text link ends up with the product name (if not overridden), so if the name changed, your post would eventually reflect it.
But, instead of just a simple text link, you could easily have a cover-image link instead. And, instead of having to generate the long-form linkage, you could just do my CG-Inline form:
... or something like that. Of course, if you turned off CGA or CGI, the link WILL disappear. It's a blessing and a curse! ;)
I've considered doing the embedded-link-info as a QuickTag like WP-Amazon does -- but the moment you do that, you lose the flexibility to, say, change the default image sizes across your site, or how they are styled/positioned, etc. Stuff like that. Certainly the moment you want to display things like Pricing, Availability, etc., you've got to be using dynamic links (bc without being dynamic, and updating every x days, using any such information beyond a certain time limit is in violation of the Amazon Web Services license agreement... it's a pain, and part of why when you start showing things like prices you need to do things like show the amazon-disclaimer thing I package in...).