Re: cross training
I did some cross training early on (tai chi, kali) but came to realize that I had far too much to learn about aikido to detract from that learning curve by bringing in other elements. I did find I was using the other art movements to see what I could do from an aikido perspective (nikyo with kali sticks is real painful). I understand the need to keep things relevant and be able to address other issues. However, I admire my sensei's perspective. He did not train in other arts but worked out with other arts to make sure his aikido worked against them. In other words, test your own art and fix what doesn't work or refine it so it does.
When I even watch other arts, I find myself looking for how I would respond from an aikido perspective or how to add an "aiki" element or component to a move or technique that looks effective. It adds to my arsenal not detracts from it. Also, if I were to decide to cross train again, I think I would look at something like daito-ryu or sojutsu or kenjutsu to enhance the elements making up aikido (especially daito-ryu since I'm interested in atemi).
Just my thoughts for whatever they are worth.