NPC's - usually just put them in as an event --> set the picture the the character you want as an NPC.

To set where they go, click the drop down menu next to Type, in the movement Pattern, and choose custom. Below the drop down menu, a button will become active (Define route), click the button and choose the directions you want the NPC to move. If you want them to repeat this over and over then make sure Repeating is checked. Once you have done, click the drop down menu in the top right of the define route screen, and make sure it is set to This Event.

To incorporate a story, use a series of events. If you are using rmxp, then click the blue cube on the toolbar to choose the event layer, then double click on a square on the grid. This will bring up the event menu. If you double click on the <> then it will bring up the different events you can use. Many speak for themselves, but others may do things you don't know. Ask Bluecube for more info.

As for the sprites, the way I stopped that was to download iDraw (search Google for it), then opened the sprites in iDraw, and saved them as pics (png. bmp.) in a folder. Then go into rmxp, and import them into the Character folder, it will ask you to set the transparent colour, choose the background of the sprites (e.g if the colour behind the sprites is green, then LEFT click somewhere on the green). Look the translucent colour blank. Press the clear button next to it if you want to make sure it is blank. Your sprites should then work. All you need to do is choose them for your characters onm the database.