Enlightenment v2 will indeed trigger an update on websites running v1. The theme hasn’t received an update in over 5 years so things are most likely bound to break, however menu icons and descriptions are not one of them since very little has changed for those features particularly.
One thing that changed was that Glyphicons was replaced by Font Awesome as the default iconset in v2, however the fix will be as simple as going to the Customizer and changing the iconset. Although I recommend you switch to Font Awesome instead as the icons are a lot more polished.
I see from your site is that you are using the Bootstrap Shortcodes plugin. Since this theme upgrades to Bootstrap 5 and the plugin you are using currently does not support it, that’s a part of your website that is likely to break. When the update comes out I recommend you clone your website to a staging site and test the new theme there.
The theme will be 100% free with all advertised features working without the need to upgrade to a premium version.