[namtih]

Option 1: I wouldn't do that. Why complicate the settings and separate options? This would also mean I should separate the option for the page per items for channels, playlists and so. From my experience as PM and developer I wouldn't do that.
Option 2: what do you mean?! From which list? Search? If so, this is a behavior for RC-user (not PC+Keyboard) so they can easily switch the search to a channel or playlist based search.
Option 3: !?!? I don't understand anything here...sorry. Can you clarify what you mean?

1) I mean the navigation entry "Meine Abos". When you have subscribed to many channels a setting of 50 could be too small to show all new videos. But with a setting of 50 it would load a lot of old videos when I browse through the channels. So I think it would be nice to separate both settings to be able to set a high setting for "Meine Abos" and a low setting for "ABOS".
2) It's also about "Meine Abos". I would like to be able to deselect some subscribed channels for this list as I don't want to have it in this list. For example a channel uploads a high number of NBA highlights each days, so that "Meine Abos" is full of it.
3) I would like to be able to disable navigation entries like "Mein Kanal" or "Liked videos". Or at least to change the list position (for example to set "ABOS" top the top of the list).

I hope it's more clear now.