Can anyone here advise or just say if there's a resource with all music engraving rules? Let's say on the highest orchestral level with all possible situations and rules - ultimate guide, book or whatever. No beginner books.
There is no book with "all" the rules, because composers are inventing new notations all the time.
The most recent "standard reference book" is probably http://www.behindbarsnotation.co.uk/
Music Notation by Read and Behind Bars are the only decent ones I could find.
But for a TRUE spec, probably your best bet is the source code to LilyPond.
Because it just isn't written down concisely anywhere else. You're almost forced to learn it by osmosis. Or just don't bother and buy Finale or one of the other notation programs available.
Music Notation is kind of read only. Practically impossible to write well.