You may be interested in preparing (real) 3000 mAh battery (aka dual-scud - with this beast + some spare regular (or also duals ) ones, You'll be probably last man on earth to face power shortage, without need for expensive and unpractical external batteries (+ facing power loss from 3.7V -> 5V -> 3.7V conversion (purists - I used 3.7V just for convenience, I know it's more complicated).

As for navigation, it's of course up to personal preferences, but I'll just say one word - Marble.

No need for long description, You check it, You love it.

Browser thing - microB (Maemo build-in browser) should be able to handle almost everything, but, just in case, I suggest Easy Debian with Iceweasel. It's slower (unless You prepare dedicated partition for ED, instead of using ext* image on vFat), but it works like Your desktop Firefox. Personally, I would scratch Opera or Fennec (mobile Firefox) - not worth installing IMO.

Also - It's obvious, but just in case - I would take small USB 2.0 HUB for H-E-N. You never know, how much USB devices You may need to connect @ once Also, if You use powered one, You can charge while "hostmoding".

For really geeky stuff, small USB wireless keyboard + mouse + capable pico projector (atom?), and You got mobile workstation with ~60 inch screen fitting inside Your fist (screen, not whole setup).