Cheap & light wide-angle/travelling setup for M43?

My doctor told me that if I want to stop feeling backpain I should avoid hiking and cycling wearing a heavy backpack. This means that long trips with my 6D + lenses + tripod are out of question unless my wife and I can use a scooter/car/train to get to our destination.

I have an Eos M that I enjoy a lot, but considering that it has very limited AF and lens selection it's not really ideal as a "do it all" camera, at least for me.

My knowledge of M43 systems is very limited, but I do know that they can produce good image quality at a fraction of the weight of a full frame setup.

I'd probably try to buy something second hand to get a general feeling of the whole M43 system, and what I'm looking for is a reasonably light body + 1 wide angle lens (possibly wider than 20mm, aperture is not important because I'd use it at f8/10 for landscapes anyway) + 1 "general use" lens.

To be honest I don't like the way Fuji cameras look, so from a purely aesthetic point of view I'd rate Panasonic first, Olympus second. If I had to pick one camera right now it would either the G6 or the GX7.

Main questions are:

a) If I find an older camera (like and older G model, or even an Olympus) second hand at a good price, is there going to be a massive difference between older and newer model, or minor features? (I know it should be discussed case by case, but if image quality is similar I consider other things accessories, and I don't care about video). I've seen a G3 on sale second hand at 90$ body only and was intrigued by the price.

b) Which lenses should I be looking for? To have a general idea of the system I'd prefer to stick to the 2 lenses I mentioned before, then if I enjoy M43 I could focus on fast primes and other things.

Thanks a lot in advance for any suggestion!