You have a lot of options. If the current finish is glossy you will have to sand no matter what you do. If you are down to the bare wood already you could go a couple ways depending on your plans. A dark brown almost black stain would look great with a bit of distressing, any future scratches only add to the look. Brass or silver/nickel hardware would both look great and could go contemporary or traditional. For painting, if it is going to see a lot of use, go distressed, upkeep of a pristine finish is a pain.

Pine doesn"t cover get, it will look distressed. If you don't like that look, see if there is scratch cover up pens.

Go to youtube and search your question. There are hundreds of DIY videos showing how to do anything you can think of.

Totally depends on the room it goes in. I love Michelle's idea but would not suggest brass hardware. You can go wild and if it were in a girls room paint it high gloss white with black handles, hot pink, bright orange or lime green with colorful handles. Cobalt blue or black for a boys room. It's a canvas so your options are endless. If you are opting for a simple refinish, go to a professional, they will make it look brand new!

yeah, take off the hardware before you start, because it's going to need updating. nickel, bronze, whatever fits your style.

also, if you no longer lock it, you might try filling the lock areas with wood filler (and sanding) before you do any paitning...