No, the final coat should be neither roller nor sprayer. For painting wood or faux wood, it's better to use a brush to lay off the finish unless you are going for a high-gloss, laquered-box look for a contemporary or Asian style. (The stroke lines are part of the cottage effect.) They should be subtle and smooth, but show. This can be done after rolling or spraying in small sections, but you need to do it fast before the paint surface dries, or you will just pull the paint off the wall-- ooops! ;~)

Kilz is actually more known for hiding stains-- I think it's that you use the oil Kilz if it's a water-based stain, and the latex if it's an oil-based stain. Its name means its chemical composition KILLS the bleed-through of the stain. They do also have high adhesion, but until you know how the paneling (and dirt, and grease, and shine products, and cigaret smoke) will react to your primer, it's a bit early to get out the compressor. :~)

On the sanding-- Bobert's suggestion (nevermind his speeling) to use a sanding block on a long handle-- that's just being smart, especially if you have strong young laborers. You don't have to sand down to the fiberboard under the fake wood, but it is a good idea just to lightly scuff ANY non-porous finish. (Giving the surface "tooth" for the paint to grab onto.)

~S~