No. Developers sometimes uses cameo from different games that they use in other games. They are not the same developer, they all may have contacted each other for usage of other characters in games.
You don't pay more for new updates for this game once you bought let say 4.1a now when other version releases you just go to your purchase library to download new versions. I know some developer tries to charge money for each new updates so far digi_b does not do this, I bought this game when it was version 3.1 and when version 4.1 was released I just download the new version in my purchased games library.