Good morning Sly,
Hello and welcome and I post my musings on two of your subjects,
1) Givi Trekker top box, big enough for two lids and its on my bike most of the time, easy storgae and out of the way when riding. I had vario panniers before (on my 2004 bike) and indeed you could fit a lid in one, but I didn't take to them. I have lone rider panniers but again only use when I have a need to carry/hold more stuff.
2) Battery charging via an optimate and fly lead.
Show off being only 31, but good to have another member of the Under 50 team.......