I removed the wallpaper from plaster and lath walls. I found a few cracks that were easily repaired but previous owners did a terrible job with patching. I would like t o get rid of imperfections and make it smooth looking. Can I use the pre-mixed USG (green lid) all purpose joint compound to do this? Do I need to use a bonding such as plastic weld first? If not what should I use? I don't want to deal with structo lite which from what I read seems hard to work with.
I would patch cracks with general purpose , any large cracks use paper tape or mesh so it won’t crack in the same place after being painting. To give a really easy nice finish after the patch work is done is to use “topping mud”, it is much lighter than general purpose and way easy to sand. I used this method on “quick skim” jobs where I wanted to change the texture type, you can use general purpose for skim but it takes longer to dry and is a bit tougher to sand. (Topping mud is not hot mud it is lighter and softer than general purpose and not for cracks).
While I have used Structo-Lite for many years without issue - if your repairs aren't of substantial depth/thickness, any discussion here would be moot.
For cracks and what not, on plaster walls, 90 Minute Setting-Type should suffice.
Just mix what you need and store the bag in a dry place. You'll more than double the coverage area, and won't have to worry about contamination, freezing, or disposing of a half empty bucket of bad mud later on.