I believe the main thing any of these coins need to do is give people a real reason to use them as an alternative to Bitcoin or any other coins.
For example, is your coin going to provide anonymous payments like Monero would?
How fast are your confirmation times, what are the mining rewards, what kind of network distribution do you have in comparison to Bitcoin?
Potcoin still has a lot of trading due to the hype and pump a couple weeks ago. Hopefully people stay interested in the project.
Yes and they need to actually be backed by real grow ops and real products that they sell. It should be like an investment in shares but you can then also use those shares to buy the product. This means that anyone who wants to buy the products needs to buy the coin first. You could also buy and hold coin like an investor then just sell to the next person that needs to buy something.