When i ranked up in orange belt in beginners everybody told me to gtfo its beginners room and started cussing at me :[ why am i being hated >.>

well. just ignore the people. dont care about them, if they dont stop it take a screen shot and report them to a GM

Ok

They are just jealous that you are improving and got a better belt then them. Ignoring would be the best option. If they continue to bother you and won't stop just pm a gamemaster(azurite name). Everyone has the right to stay at any public server they want. Or you can just ask them nicely to stop.

Actually, the reason they asked you to get out was because beginner rooms are for white and yellow belts, not orange belts. But since you actually earned your belt in a beginner room, you were able to stay, if you leave and try to comeback, you'll notice that you can't get in beginner rooms anymore.

I don't know why, but when I join a custom server to play a different mod, they say either to go out, that the rooms is private or they kick me from the server. I think they kick me because it suddenly appears "not connected"...
This is really annoying, I couldn't be able to play a single custom room because of this...
Please, people, IF YOU WANT TO MAKE A PRIIVATE ROOM PUT A PASSWORD TO IT OR NAME THE ROOM "PRIVATE SERVER" OR SOMETHING LIKE THAT!!!

Not everyone knows how to put a password on their server or to change the server name.

You were kicked because either the room really is private or you were about to win. It is their server and you can't do anything about it. You can always make your own server and wait for someone to play with. Saves you the trouble of playing with short tempered ops.