Q: do I need any API key to use Google Map?
A: since new version of Goole Maps API released you do not need any API key.
Q: I see static image instead of Google Maps frame in the CKEditor/TinyMCE?
A: it is OK, it is just a preview in area of my editor. In the page where HTML code (which you a edit with editor) is displayed, Google Maps widget is shown.
Q: I see static image and on the result page too?
A: As it described on product page, this plugin is compatible with CKEditor 4.1 and newer. Probably you are using CKEditor 4.0. Please, update it (it is very simple - just rewrite all files excluding config.js
with their newer versions from CKEditor's official site).
Q: on some specific (big) map dimensions I see only a part of map in the editor?
A: Google allows to get preview of limited part of map, but the map displayed on the result page will contain full map you have built with the plugin.