Your goal of censoring chat does not require a bot. It requires javascript. But I'm profoundly against censorship, so I won't aid you any more than to tell you that you are not looking for what is commonly known as a bot. You're trying to add on some javascript to the existing chat module, which is itself powered by javascript.
But as for the simple word replacement, please again state precisely what you want to do. It sounds like you just want to replace all three of those variants with the word Project, which is simple enough. But your wording, "the sitename coding for 1 this link", is a little vague. Please state exactly which words you want replaced and what words you want to replace them with. Also, it would help to have a few live examples of pages that require the replacement you're requesting.