-You can add NPC's by opening the event menu and setting the char set graphic to the NPC graphic you want, then have the event be a push key on the same level as the hero, then make a show message command and type whatever you want into the message box. This is a basic NPC that will show the message you entered when you walk up to it and hit enter.
-You can make a non random battle by doing the same thing as above, except make it "On hero touch" instead of a push key, and instead of making a show message command, make a "Start Combat" command. This will bring up a new window that will let you select which monster to start a combat with when the monster touches you.
-The title and gameover screens are changeable in the system menu in the database (F8). Keep in mind you need to import title and gameover screens into your game if you want to use ones other than the default