Bathroom wallpaper removale Help and questions

Hi this is my first post so if I break protocol please forgive me. I also have limited use of hands and shoulders so if my typing is poor again I ask your indulgence. My wife and I are redoing the entire house, making room for my son. (disabled vet) Removed 60 year old wallpaper from bathroom. Top came off no problem and have begun working on backing and glue. I've noticed many folks here recommend using gardz to seal the wall. Can not find Gardz in my local stores. Another suggestion is an oil based primer. Any brand names? I have cover stain by Zinsser and Kilz complete, both tinted a light blue. I bought these to test on untreated 60 year old dry wall in the garage. Can these be used? I also have a question about skim coat. Can anything labeled joint compound from (Home Depot, close Lowes miles away) be used? Is there something I should be looking for on the label, questions for sales person, name brands. I have a Sherwin Williams paint store fairly close, do they have a primer that can be used? Name? Thank You all so much, I really appreciate any and all comments. I'm old but this is all new to me.

 

The Zinsser oil based primer would be my choice of the two you listed. Just keep in mind it's worth the effort to remove all of the glue you can first. Regular joint compound would be the best single product for skim coating. Finally, Sherwin Williams would be a good place to get both primer and paint.

 

Get the joint compound with the green lid, it's an all purpose mud and has more adhesion properties than the others. You'll want to thin it slightly with water so it spreads easier.
Most any oil base primer will work. Gardz is the only water based primer that will work. The primer both seals any leftover wallpaper paste and any exposed gypsum [where the drywall paper is torn]