We were there this past week. We got to Epcot right around 9am on Friday due to a breakfast ADR at Ohana. It was the longest bag line my DH waited in the whole trip. I recommend either getting there early or waiting until after the 9am rush.
The only time all 4 of us had to go through metal detectors was on the weekend. They seemed to be screening most everyone. Otherwise I was selected 1 other time, kids no other times, DH 3 times. It was quick and painless. Literally a minute each tops.