Vinegar is used because it has a know acidity - the acidity of lemons can vary between varieties, growing conditions, how ripe when picked, etc. I have seem some things in middle eastern cooking that used lemon juice but they were not for long term shelf storage.
You should use "pickling salt" for your pickles ... it will not cause your brine to get cloudy - caused by minerals in table, kosher or sea salts. Some of the minerals can, in addition to clouding, cause softening of your pickle or can impart a bitter metallic flavor. Of course, that is for long term storage pickles - probably not as important for a short term refrigerator pickle.
"It ain't what you don't know that gets you in trouble. It's what you know for sure that just ain't so." - Mark Twain