It's not virtual property, it's intellectual property and courts have plenty of experience dealing with it.

The way that the program distributes temporary copies, the fact that it's a virtual world and that's it's an open sourced simulator are completely irrelevant.

A common well tested operating system that's been used by dozens of other groups will contain far less bugs than code hacked together by your own small bunch of developers.

It doesn't mean that you don't test it or that you test it less. It's simply means that other people will be testing it as well.

The solution is a market. A real one, where people actually trade with each other.

You need genuine demand for goods, regular food intake, equipment that breaks etc.
You need an open market that allows people to trade between each other.
You strongly favour specialists over generalists, this forces people to interact in the market.
There has to be mechanisms to remove wealth from the game, this can be transaction fees, regular taxes, destruction of goods through use, consumption of goods such as food. Demand must always be higher than supply, if everyone has the best armour, best weapon and tonnes of food, the economy is broken.

The system is self balancing. Everyone needs all the goods and everyone needs to interact with the market. If weapon smithing is lucrative for some reason a genuine supply/demand market makes weapons cheap enough that it's no longer the case. There will always be short term advantages to being in different groups but they balance as the market pushes people to correct for it.

The game administrators have two ways of influencing the market.
By tweaking the tax system and economy dampers they change the overall availability of goods.
Adjusting the demand for a particular good or the rate that it's produced will change the number of people in a given profession. This also impacts on the overall economy.

I don't think safety rails are necessary. A game with a dozen people will make the economy start to tick over. However if safety rails are required (NPC's producing food etc) then the prices should be punative. Selling at least 5x more expensive than a human farmer would sell the product for and buying at least 5x cheaper. People should not regularly be buying or selling from the NPC based market.

The big downside to all of this and the reason the game developers don't do it is because it forces you to interact with the market. Which isn't cool if you just want to go around and punch monsters.

I think the goal of Gnote is to have a good note application like Tomboy that doesn't require Mono. Any killing of Tomboy is just a side effect.

If Tomboy died the core developers probably wouldn't switch but many of the minor contributors will and all the future contributors will including the new eyes that see a better way to structure something or a really nice new feature. Gnote will continue to grow.

You have identified the key problem nicely in your question. How to maintain your changes when the base changes underneath you.

The first thing I recommend is to go back to your basic OOP structures. If you can, inherit and extend rather than modify their code. The interface will change far less than the internals.

If you have to modify the internals try and keep it as contained as possible. Consider creating new functions rather than modifying theirs. Try and collect as many changes together as you can, each function changed is a pile more work.

When you are updating to the newer versions try and do a three way merge, it makes it far simpler. Many of the distributed VCS like git have it built in or you can use tools like kdiff3 to do it manually.

Rowing is an interesting sport, it works a wide range of muscle groups and is non-impact. You can row in groups or by yourself and in most countries right through the year.

The biggest downside in my view is that the water is generally flattest at dawn so you have to be up early.

With sculling you should be able to move the boat by yourself, a decent quality boat is very light. Rowing in the winter is certainly possible (if the water doesn't freeze), the risk involved is drowning due to the cold water before you can get back in the boat. Practice improves the time to get back in and experienced rowers rarely fall out.