Everything you say is considered to be in character, unless you’re asking a mechanics question, describing what your character’s doing, or asking the DM for additional information, and similar types of things.
Once said, it is said. So if ye said to your party while in the presence of someone: “So tonight we’re going in this dudes house and robbing him, right?” (or the like), you will have actually said that.
Communication During Combat
Speaking is a free action usable on your turn of combat, but you are limited to short sentences. You may not respond to a question given to you until the start of your turn.
Having a telepathic bond allows one to ignore this rule of communication during combat.