I'm probably not the best person for this job, echo, since it is my first critique and I'm not terribly familiar with RP sites, but this will get you started. Remember, take what you want and leave the rest!
Design (Colors, codes) - I like the colors. They evoke the night and fit the subject matter since cats are so nocturnal. The colors compliment each other well, and text colors are easy to read, even when the boxes are highlighted. Your on/off buttons fit the theme nicely. You might want to consider creating new purple cat graphics for the Infocenter to match your theme. The default icons look a little jarring otherwise.
I love the 'Warriors of the Moon' graphic with the flare in it! Very nice! Kudos to the designer who did it.
I'm a little less sure about the the "O"s in the banner above it. Is it suppose to be two moons? My first thought was that it was 2 bites of Swiss cheese -- and that might not be the effect you are looking for! Suggestion: look for or take a photo of the moon and use it instead.
Using text links for Home, Help, Search, Login, etc works well in this case because you have a lot of graphics in that area. Good choice.
There is 24px × 24px broken image just below the Infocenter on the left side. The URL listed in Properties isn't an image URL. It is the URL for your forum. Might want to look at it.
Categories and Boards - This is where my ignorance probably hurts the most. It looks good to me, but other RP hosts can give you better feedback. Sorry about that!
Love the lunar phase chart in the left side table!
Activity - Various clans are empty right now. Is there any posts you can add to make them look a little less forlorn?
The news box in the side table says "(news goes here)". I'd suggest posting something right now. Perhaps you could mention that your forum is now open and accepting staff spots?
You've got "Moon and some news..." in the side table above the moon chart and below the news box. Did you want it ABOVE the news box as well? With it situated between them, it looks like it might be in the wrong place.
Overall, you've got a lot of activity started, echo. Looks good!
Rules - A bit confusing and could use tightening up. Example: 1) no Advertising, and if you do, don't beg for members, So does that mean there is advertising or not? You probably should spell it out for them. Will you take simple links but no begging? Then say so.
You probably could combine the "Don't give us headaches" and "No ranting on bad things" rules into one rule; "No ranting. If you have problems and need support, please calmly email the staff."
Ease of Navigation - Easy. Even I could do it!
Overall: It looks pretty good, echo. There are a few things I'd change and tighten up, but it looks like you have a good site on your hands. I'd rate it 8/10 stars.
xD, just wanted to say: I know the old graphic at the top was a bit goofy, so i re-made it a couple minutes ago. The clans, well, some people liked one clan, mainly Amberclan, we will fill the rest soon. Thank you!