Mine is 2 inches wide by 3 inches high. I measured from the front of the handguard. This may not be exact, but that is roughly the measurement. I used an old tape measure and it is hard to line it up exactly without taking the handguard off, but this should be sufficient.
yes. i cut out a small square section to accommodate the pin. i’ll admit thats its not the prettiest bit it doesn’t bother me as its not visible with the card attached.
can’t help u with the dimensions of the briley handguard as i run oem handguards but i would think that having the charging handle installed (regardless of brand) would be your wide point especially if u run a light/side saddle on the opposite side as i do.