Online sites offer "unsearched rolls" and you shouldn't believe it for a minute. I buy bank wrapped rolls and sometimes customer wrapped rolls from banks only, but not Internet sold rolls. I occasionally buy U.S Mint wrapped rolls boxed in original packaging. Do you really think someone would wrap up coins without looking to see if they have the valuable variety?
Buy coins only from reputable people you trust. Do your research on the coins you want to buy.
I learned to grade watching PCGS videos on grading, using their photo grade section, and by building my own grading sets. Like anything, practice. You can do this!
Get a 10x loop to examine coins for grade and 30x loop with light for finding errors. Add a 1000x USB microscope, a scale accurate to 100th of a gram, and a millimeter ruler to search out varieties.
If you need help identifying a coin, join a Facebook coin group and post good, close-up images of your coin. First try to find the coin yourself in the web sites I've provided. For pictures, start with pictures of the entire front and back. Add a few zoomed in pictures of the error. This will help, focus that camera! Finally, add a proper question as to what you want to know so you can get a specific answer.
You buy coin rolls from a bank and you drop them off there too? Please don't, you will make the bank buying for you much happier to service your growing hobby. Many Credit Unions have coin machines you can use to drop off.