Question one, to answer that with 100% is near enough to impossible. The products you mentioned might work well, they might not, it is dependent on many factors.
The market you are selling into, the market economy, the price, your competition and so on. This is where some serious research and some level of test marketing comes into play.
These practical things will give you the data that you base building your business around.
In regards to what the most demanded in the market would be, it's probably safe to say that the well known brands are usually going to be the most popular, but again, it always comes down to determining market factors such as price and so on.
In regards to avoiding electronic accessories, it's a market that stays relevantly solid through thick and thin, so maybe one you should look at a little more closely.
"What kind of craft and hobby items?", that one is a decision you would have to make, based on doing your market research.
Sporting goods, I'm no expert in this field of product, however if we are talking about eBay here as your selling platform, brand names at the right prices are always a good idea, but I think in this genre in general, price may well be the determining factor for buyers.
All of your questions really do relate back to good old fashioned market research in the beginning, then advancing what you have learned during that process into the next phase, test marketing.
Those two processes can take a long time to ensure they are done correctly, but if done correctly, can provide a very solid foundation to build an online sales business upon.