playnite-library-psn VS PlayniteExtensionsFeatures

You can use tags, some library plugins can tag those games automatically (or there are plans like https://github.com/XenorPLxx/playnite-library-psn/issues/8). The main Xbox library add-on doesn't add game pass games unless you run them at least once.

True, but it's still there. I'm using it. https://github.com/XenorPLxx/playnite-library-psn

That depends on what you want - old games or modern? What kind of cover? Vertical, horizontal, or square? I've made a list here, but if you've got more specific questions feel free to ask: https://github.com/Jeshibu/PlayniteExtensionsFeatures/blob/main/metadata.md

I keep track of what libraries support what here: https://github.com/Jeshibu/PlayniteExtensionsFeatures/blob/main/libraries.md

There's a list of library integration capabilities here: https://github.com/Jeshibu/PlayniteExtensionsFeatures/blob/main/libraries.md. In Playnite, you can select to import playtime once, always override, or ignore. Most popular libraries import playtimes with exception to Ubisoft and Battle.net

That is possible if it's a game from one of the libraries with "Play time import" checked here, and if Settings > General > Import playtime of games in library is set to Always.

You can look up what libraries support playtime import via the library feature table here: https://github.com/Jeshibu/PlayniteExtensionsFeatures