Just to preface, I'm not a camera geek at all, so I don't know much about the technology. Our equipment is very old, entry-level stuff.
DSLRs
We have two DSLRs, a Nikon D60 and a D3000, both have very similar specs, but the D3000 is the next version of the D60.
The D3000 is fitted with a Nikkor VRII 18-200 lens and is the camera that is taking 90% of the pictures on the blog. The D60 has a Sigma 10-20.
Neither does video, so I've been thinking about upgrading either to a D7100, or go full-frame with a D610. Not in too much of a rush though.
I'm very happy with the Nikon image-processing. I'm not a fanboy of anything, but maybe Nikon products come close.
Point and shoot
Our point-and-shoots are the Nikon AW1xx line. It's supposed to be dive-resistant to 10m, but it's not. We started with an AW100 at the beginning of the trip, drowned it while snorkeling. Bought the next version AW110, drowned that one too. The AW120 came out by this time, but I didn't need all the new bells and whistles, so I re-bought the older AW110 which I'm using now.
Even though I'm not happy that it's not complete dive-resistant as advertised, I very much like the AW image quality. It'll still survive a heavy rainfall though so it's our default on-camera bike. I keep it in my tankbag and whip it out with my left hand to take all of the riding shots of Neda in front of me.
Kinda like this...
Other things the AW could improve on is that the start-up time and auto-focus is slow. Between the AW100 and AW110 failures, I bought a Lumix DMC-SZ5 which had an amazing start-up time and AF, but the image quality suffered, so I'm sticking with the AW for on-board shots.
Answers
1) A couple of friends have shown me their mirrorless cameras (edit: One of them was an Olympus OM-D E-M10). They rave about the compact body and lenses for space savings on the bike. Seems to be the only benefit over DSLR. From what little I know of the technology (I'm expecting a mirrorless expert will chime in soon): Lower battery life, lack of optical viewfinder, flatter depth-of-field, slower auto-focus, means I am sticking with DSLRs for a while longer.
2) I love my huge 18-200mm! It is very versatile and is my favorite and I was thinking about getting an 18-300mm to replace it. At the Misano MotoGP, the 200mm was very inadequate. I was sitting next to a guy with a 500mm which got great shots, but it may be too big to carry on the bike.
As you can tell, size and weight figure negligibly in my decision-making.
3) No filters, just a clear one for scratch-protection. We had a polarizing filter, but it was an extra step figuring out the orientation when all I wanted to do was point and shoot most of the time, so it's sitting there unused in the camera bag. I think I have many outdoor shots that didn't turn out because I wasn't using the polarizer.
4) We only have two lenses and they are permanently affixed to each camera, so no need to clean the insides. I carry one of those lens cloths in a small pouch to clean the glass once in a while.
5) Yes, the bag is very irritating however I like to have the camera ready to whip out at a moment's notice and a backpack takes too much time. Some people carry the camera in their hands or around their necks, but our time in Latin America made me wary about having an expensive item out in the open so in the bag it stays until needed.
If security is not an issue, our friends Jill and Curtis have found a neat solution:
http://chasingadventure.ca/2013/09/25/gear-review-capture-camera-clip-by-peak-design/
6) I have a very cheap $30 Vivitar all-flimsy-plastic tripod that I break out for night shots. Other than that, a steady hand and taking a hundred shots and picking the two that turn out...
Again I'm not a camera expert, so all the above is just my non-informed opinion.