Hey Kapselidakis,
Make sure to have a look at our demo:
demo.compojoom.com/hotspots
. Also on the left you'll see a live demo option - it will get you access to a joomla instance with hotspots on it. Not version 5, but 4 something. I need to update the site to use version 5.
About your questions.
1. Yes and no. You can put if you want 1 million markers. that is not a problem. But he user will always see a max. of 100 locations in the menu. (with pagination he can go to the next page etc). When he zooms in, the we show another 100 spots etc. (or 20 - depending on your setting.) A good thing to read is that here:
compojoom.com/support/documentation/hotspots/ch05#id359747
2. Once your subscription expires in an year you lose access to support and to new versions of the software. The version that you've downloaded will continue to work as expected and there won't be no limitations.
Hope that this answers your questions
If something is unclear - just ask
Regards,
Daniel