I live with 3 other girl roommates who have all lived at this place one year longer than I have. I answered their "looking for a roommate" ad on facebook and moved in last June. We get along just fine, and I'm actually quite close to one of them now but I have a couple issues.

About a month after I first moved in one of my roommates bought a cat. She did this without asking me. The other two roommates knew, but I was not informed. I just figured whatever, I just moved in, they probably just didn't think to mention the little Anne Frank kitty. It is in our lease that we can not have pets unless approved by the landlord (this feline is not). I have a niece that is allergic and therefore can't come over to my house. Plus I'm just not a cat person. I find them annoying and pissy animals, especially this one. It's no secret that I don't like the cat. It's snuck into my room on several occasions and ended up on top of my newt tank and I'm worried that the dumb shit is gonna knock the tank over effectively ruining my stuff and killing my newt. There's a whole list of other reasons it's a hassle that I won't even bother putting down.

Luckily the animal is gone for the summer, but it will be back in September and I need a way to like, I don't know, lay down ground rules or something. Like, cat only upstairs (where the cat's owner's room is). Or cat needs to get declawed. Or KEEP AN EYE ON YOUR DAMN CAT AND DON'T LEAVE IT AT THE HOUSE WHEN I'M THE ONLY ONE HOME FOR THE WEEKEND AND EXPECT ME TO TAKE CARE OF IT CAUSE I WON'T!

Second issue is having company over. They have a few friends that come over on a regular basis. That and they leave the connecting door to the neighbor's place (we live in a duplex) unlocked so the neighbors can come in if they want (They're friends with the neighbors, I don't really know them that well). They do this stuff without asking me and it upsets me. Especially when they get angry if I have a few friends over to hang out in the living room without asking them.

It just seems like a "You haven't lived here as long as us so you don't have as many rights" kind of a deal and it makes me angry. I've lived here for a year, I pay the same amount of rent, I have all the same rights they do.

What's the best way to go about discussing these issues with the roommates in your opinion?