I’d like to include the new ruble 20BD to my font. Will Glyphs support it and is there anything special I should do/know to implement it?
It already is implemented. Add a glyph called ‘ruble’. For things like this, you can check Window > Glyph Info, or simply add the glyph uni20BD and see what happens (perhaps with Font > Update Glyph Info).
Unicode 7? Has there been still another update?
Yes, Unicode 7.0.0 was announced on Monday:
Unicode Standard, Version 7.0.0