wheel lock

Hi all, first post. I'm considering a Multicharger for myself in the future. Is the frame/wheel lock the version that requires you to leave a key in it whenever its open or does it just require the key while opening and closing the lock? What is the length of the rear luggage rack? And maybe...

Can anyone recommend a frame lock that would fit my Agattu 7? It doesn't look like there is much room to fit one so would be interested to know what other people have fitted.