Firstly, it's a really bad idea to post your email addresses - it's an invitation to spam - and I've asked the Hosts to remove them.
You can create an alias with anything you like before the '@' provided of course that it hasn't already been taken. However what follows the '@' can only be @icloud.com - @mac.com addresses can no longer be created, though existing ones will continue to function (and have equivalent @me.com and @mac.com versions).
As your current Charter.net address is (something)@charter.net and you are going to change it to (something)@icloud.com you are still going to have to notify all your friends as it is a change of address.
You don't say whether your charter.com address is completely independent of your iCloud account or whether it is its login (though if you have an @mac.com address that is likely to be the login). If your login is any non-Apple address you can change it to any other non-Apple address, but you cannot change to you @mac.com, @me.com or @icloud.com address (or alias address), and if your login is an @mac.com address you cannot change that.
When you add an alias you cannot access it as a separate account in Mail (it's not an account which is why when you try to add it you can't find a password for it); you can access and use it as the 'From' address as indicated in my post above.
More information on aliases here: http://help.apple.com/icloud/#mm6b1a490a