If you want to turn the signature off in the future, you can come back and edit your post. If you have specified a signature in your profile, the box will be automatically ticked for you. You can search any forum that you have permission to search - you will not be allowed to search through private forums unless the administrator has given your the necessary security rights to do so. Announcements are made by the administrators, and are meant to be a simple one-way communication with the users. If you wish to discuss announcements, please create a new thread in the forum or e-mail an administrator, since you cannot reply to announcements.
Some words are censored.
This censoring is done by a computer simply searching for words, and is by no stretch of the imagination 'intelligent'. If you make a post in a thread, you can choose to receive email notifications when new replies are made. This option is set when you make a post and can be turned off by by editing your post. Registered users only are applicable to receive email notification and they can set in their profile whether they want email notification on or off by default. If the administrator has enabled message icons, you can specify a graphical icon to accompany your post.