For the first part, mIRC is not responsible for handing out modes in your channel. Its not a channel service. Enough said.
Again, the second one about the kickban is the same, the fact is you send the command to the server and its not the clients choice in which order they occur in. Silence ban? If by that you mean just ban the user without the kick, again, thats server related.
mIRC is a client that allows you to use all the features of the standard IRC protocol with ease. It does not run channels or networks out of the box, thats why they gave you scripting.
