Here's my opinion. If you are planning on choosing a new colour, I would strongly suggest using a lighter purple, or if you plan on a whole new colour, I would go with Orange. I think orange would look very appealing as far as coloured names go, but a lighter purple for sure, it would look much more inviting to me.
As for your "stars"/disk things, I would suggest that they have something to do with your groups name, since your group is immortals, perhaps you should do something that relates to said name. Examples, perhaps you could do little gladiator helmets, or little skulls with crossbones behind them (this of course represents immortality among death). I could go into more detail in this if you wanted.
As for members joining, I would expect that you want some money off of this, so your best bet would be to at least require 10-20 dollars for new members, but since you are only accepting 5, perhaps $25 might be appropriate.
Please take my suggestions into consideration, I can elaborate more if you'd like.