Hey Aniceto, these sound like nice features. When you are ready, file a new "Feature Request" against the "Marketplace Plugin" component. This is how these features begin to be incorporated into the plugin.
Some comments below.
Aniceto P Madrid:
Show in grey, or marked in some way apps which are not available for the current portal. Don't let the user to purchase it
I don't think they should be restricted from purchasing. For example, one might wish to manage the set of apps they have purchased from one portal, for use on other portal instances elsewhere in the company. In any case, they will not be able to download or install because of the incompatibility.
Add a selector/checkbox to hide/show the compatible apps with current portal
Only apps installed in my portal which have updates
Only CE, EE or both
And of course the ability of being notified when a new version of an app, purchased or not by me, is available.
Yep, these are really good ideas! The notification is in the process of being implemented as a "follow" kind of feature, where you can "follow" and app (to receive updates), or even follow an author or company (to receive notifications about new apps).