Can you use interior satin paint on hardiplank?

Can you put a semi gloss interior paint over a wall that was painted with a flat paint? I am painting one of the bedrooms in my house with Valspar Signature semi gloss finish paint. What I am getting is spotting or something you can see the roller marks on

I just finished pulling down the old paper (at least 20 years old) and most of the glue stayed behind. So did the mold and mildew. What is the best way to address this and prep the walls for paint. This is in a small bathroom…..

I will be painting my kitchen cabinets (paint over an oak stain). Can I use a good quality latex paint or does it need to be an oil based paint?

My kitchen cabinets are in good condition. I want to paint over the oak finish. Do I need to sand them first, or would a good scrubbing with a teflon sponge be enough?

Red brick with some black. The roof is black and the trim and windows are natural which is beige. What color front door would you suggest? I am painting the shutters black. The back door is going to be painted a little darker than the beige.

I was in a Walmart looking for a gallon of white paint. Bright white, not an off white color. They were out of stock and I asked about using a light base? It’s very white but I was told I could not use it without tint being added. I ask