Dunno what you mean by bookmarks but CygnusEd does everything you mention, except maybe the automatic window arranging, but it can display multiple views of the same file.
It's also very fast even on nonexpanded classic machines, there was new version released last year and it's been recognized as one of the coolest editors by Amiga users for many years.
Otherwise I'd say CubicIDE but that's very heavy though it provides a ton of language oriented features (never tried it but been hearing about it for too long...)
