Why do texts from my computer show that they come from "myname"@icloud.com?
If you open Messages, then go to Messages -> Preferences -> Accounts -> "myname"@icloud.com, you can see the option to select where new conversations are started from. For me it lists my iCloud email, my personal email (which is my iCloud login), and my cell number. Choose your cell number from this list and everything should be OK.