Why would a normal user want to launch a node in any mode other than "light" , does full or fast give any advantages in sending transactions ?
Is there any difference between transaction sent from full and light nodes ?
There is no difference between sending a transaction from a light client or full node in terms of speed of transaction, as far as I know.
By hosting a full node however you are helping expand the ethereum network. Ethereum has come such long way over the last year that I think most of the benefits of running a full node no longer exist. If you did it its mainly because you are interested in Ethereum and want to participate.