You scuff up existing paint for two reasons. First, you want to get rid of any oil, grease or dirt trapped in the top layer of paint. This is the stuff that cleaners and degreasers can't get off. The second reason to scuff is to set up a physical bond for the new primer and paint to adhere to. You want to give the old paint some tooth so the new sticks better.
You can put it around a room and probably follow immediately with the finish coat. It can be applied with brush or roller.
Don't ask friends to help you paint. Basically, you are asking them to give up their day off to save you money. You don't want to be first on the list when your painting buddy hits you up to help him move do you?
THE NARRATIVE. First look for the narrative, simply describe what you see. Who or what is depicted, what's going on? If you see people and things, the painting is figurative; if you see lines and splashes - go for non-figurative. The name of the painting might come in handy, especially when it comes to Dali. What seems to be more important for the artist - representation or expression? Compare the paintings in the styles of hyperrealism and expressionism - you can always tell if the images look idealized or expressly distorted. Notice the feelings you get looking at the painting, the general impression produced by the entire painting and its elements - later you will dig deeper to understand what inspired those emotions. There is a reason why you like one painting more than the other. Your taste in art is as unique as your taste in food or clothes, inspired by your background, upbringing and even professional expertise.
Alkyd has solid advantages overriding the slight cleanup in-convenience. It is exceptionally tough and very resistant to scrubbing. It stands up well in the trouble spots - trim, bathroom, kitchen. And it is easy to apply, producing a smooth, even finish free of streaks and brush marks.
The first step is to cover the surface with a coat of paint, using your regular paint brush, or spray, or roller. Then, while the surface is still wet, take the dry stipple brush and energetically with short strokes drive the ends or the bristles into the wet paint. Be sure not to brush across. The result will be clusters of dots. Every few minutes wipe the brush with a cloth, to keep the bristle ends clean and dry.
Knock down texture is basically a orange peel that is sprayed on and allowed to "set-up" for a minute or two then gently "knocked down" by running a 6" drywall knife over it, "knocking down" the surface of the texture. Although knock down is a flattened version of orange peel, I suggest you do not use a spray can of orange peel, the knock down comes in its own spray can and the results are much better, again experiment before spraying it on the wall. However, If ever you apply any of the textures to the wall and are not satisfied with the results, wash the texture off immediately before it dries, then allow the wall to dry and try it again. Once you have the texture applied to your liking and you have allowed it to dry, you may want to paint the patches a couple of time before painting the entire wall, especially for walls where the paint to be applied will have some sheen. Multiple coats on these areas will make them blend in, unnoticeable, with the rest of the wall. You will know if the patches need more coats of paint, because the patch/texture will have absorbed the paint causing the spot to look duller than the rest of the existing wall.