Sage, most of the ceiling textures that I've removed soften very easily with water, just sprayed on with a garden sprayer. When you get it thouroughly soaked it comes away like porridge. DO NOT scrape it away dry, as some of them contain asbestos. Scraping is a two-handed job, one for the broadknife, one for the dustpan that you're holding underneath to catch the porridge. Use dustsheets, and if you are messy, dustsheets with plastic dustsheets under them. Hire cloth dustsheets, plastic alone rucks up.   Expect to find horrors beneath. ceiling cracks, bad drywall joints, etc. Wash the ceiling before repainting.
Rapaire, after detergent washing (I'd use sugar soap), use a power sander. A cheapo 1/3 sheet finish sander is about US$10. You can find out about wax by wiping with water, with wax it will 'bead', without wax it will stay as a sheet. Use a specialist 'smooth surface' primer, PARTICULARLY if the surface looks varnished. Varnish is very difficult for paint to adhere to. If you suspect dampness, mix a specialist mildew killer in the top-coat.
Not all 'wood panelling' is wood. the cheaper kinds are often printed paper on particle board, varnished.
Wash a new cheap roller sleeve thoroughly before use, they throw off fluff. After using shellac or oil-based paint, throw that cheap sleeve away (They cost about US$1 here, costs more in solvent to clean them).
Acrylic paints are better applied with a different brush than the one used for oil-based.
Enjoy the painting.   The prep is the crap part of the job.