The Shutter speed and aperture can be coupled togehter (move one and the other moves too) in the "E" if you want, but they are not coupled to the meter. The Shutter speed and aperture are always coupled to the meter (move one or the other and the needle moves) in the "F" but they are never coupled to each other.
My widest lenses for 6X6 are the 50/3.5S and 50/3.5 PS Zenzanons for the SQ series cameras. If I need something wider I will use a 50/4.5 Zenzanon PG for the [6X7] GS-1. So far I haven't been tempted to get a 40 for the SQ cameras and my widest RB lens is a 65. My widest Bronica ETR series lens is a 50 but I have a 35 for the Mamiya M645/J/1000S cameras. As a walking around lens in 6X6 I like the 65/4 Zenzanon PS. It's wide but not too wide.