1. About host being afk before game starts.
It's all happened before, we join a game, wait for a long time and the game finally fills up with 10 people. However, the host decides to walk away (really don't understand why you would start a game and walk away). Then everyone in the game starts to yell at the host yet he is probably watching TV or eating something.
I suggest to create a host-afk function. For instance, if the game has been filled up completely, and yet the host has not made any actions (talk/auto-balance...etc) for a short period of time (I suggest one minute), the other players can vote to kick the host and assign to a new host (simply changing the host won't work...cause he's afk maybe? =_=). This way players would not get angry and wouldn't need to search for another suitable game.
2. Your hero control and statistics whilst disconnected.
Many players would certainly use the disconnected hero as means of helping themselves in the game, afterall their team is one person short. However, a lot of bad players would deliberately feed that hero either to help set themselves up or they simply dislike the player. These acts would cause unfair KDR adjustments to the person who disconnected. I suggest to make it the way that whilst a player disconnected (for whatever reasons), their kills or deaths or assists would not count towards the player's statistics.