removing wall paper frieze

If the frieze (border) was placed over wallpaper then the residue will simply come off when the wallpaper is removed. If placed over emulsion then if you have a wallpaper steamer then loosen with that first. Then spray with a stripping solution and then work the residue off with a wallpaper scraper tool or a rough sponge. For a stripping solution try just warm water first and if that fails try cider vinegar, fabric softener or you can use proprietary wallpaper stripper. I would only use the wallpaper stripper as a last resort as I always try to avoid harsh chemicals.

The best thing to do is to use a steamer and scrape it off the walls as you scrape off wall paper. In terms of preparing the walls all you need to ensure is that there is a smooth surface with no residue left on the walls and that any holes or plastering which may need to be done depending on the age or the condition of the wall is completed.

Try using a steamer to soften the backing before removing it. Use sugar soap to prepare the walls, fill holes

This stuff can be a pain in the back side, wet the wall down get a good professional scraper and scrape it section by section. Let dry thoroughly then power sand down well then wash down with sugar soap. You could try mixing a Bit of baking soda and a cup of vinigar in with the warm warter prior to scraping this may help immensely.

I would personally use a steam stripper to get rid of the residue or soak it in hot soapy water and scrape it off being carefull not to scrape all the emulsion of underneath it

It's old paint under paper that needs rubbing down until it is smooth before painting.

I would use a wallpaper steamer to remove all wallpaper and residue.
Then once the walls have dried,prep the walls by sanding them to de nib them. This will remove any dried bits of wallpaper etc.
Then apply a bonding primer such as 'Bulls Eye' or 'Peel Stop'.
This will prevent the new paint from cracking once applied.
Cracking in new paint occurs if you paint straight onto walls that have been stripped of wallpaper, because the wallpaper adhesive reacts with the paint, hence the need to use a primer/sealer.