You can and should look the part up yourself before going into a parts store, or take the old one with you. There are multiple versions of every engine sold these days, and the parts are often not the same, even though they fir the same engine you have.
Amazon has parts lookup, RockAuto has an even better one.
No! don't do that. Don't be realistic at all. It's better to berate the clerk at the parts store for your shortcomings.
Some folks should leave mechanics to the mechanics.