The above responses are great. To cherry pick one or two of your questions:
- I use Google calendar sync. This synchronises my Outlook calendar with my gmail calendar, and my gmail calendar I share with my wife. I don't actually 'use' my gmail calendar for anything - it is purely a repository for (a) making sure my wife can be across what I have on, and (b) back-share so I can jump into my gmail calendar and see what my wife has on
- I would definitely advocate maintaining just one system. Personally, I've put together a spreadsheet to suit my way of deploying the GTD methodology, and I use SugarSync so that I can access it at home, at work, online, etc. I have my tags (areas of focus) set up to allow me to keep track of what relates to what part of my life - eg "w-itt" (work - info tech and telecoms), "s-dev" (self -development), etc etc
Do, or do not. There is no try.