endless iterations

Not sure how to word this...

I'm looking for information on castles? In particular the keep, which was a residence for the nobility as well as a last line of defense.

Some questions include:

• Wikipedia only talks about English, French, Italian, and Spanish castles having keeps. Did castles in northern, central, and eastern Europe not have keeps, or is this just a matter of fewer English-language sources on, for example, German, Danish, and Polish castles?
• If you know of any good diagrams or floor plans with labels of castle keeps - both the kind of "generic" cross-section illustrations you see in children's educational books (the larger and more visually detailed the better!) and of specific real-world castles. Preferably castles that actually served as fortifications in addition to residences, rather than castle-esque palaces like Neuschwanstein Castle. It's difficult for me to reconstruct spatial information with text, so visual aids are helpful. It's very hard to find good educational pictures with an image search these days, there's too much AI-generated inaccurate bloat in the results.
• Relatedly, photos or illustrations of the castle's interior.
• Who (if anyone) resided in the castle, aside from the noble that owned it and their family, and the servants? Also, more information on the duties and types of servants who would have been present in the castle.

I, um, am sorry if this is too broad. ^_^;