I have no experience with the BAe-146, so I cannot answer that aspect of your inquiry.
Vref (landing) speeds for the EMB-145 range anywhere from about 110-135 knots depending on aircraft weight. The final approach is typcally flown 5 knots faster than this, maybe 10 knots faster if gusty winds exist. If category II
/III (low visibility) conditions existed, the landing speed would be even higher, as this requires a smaller flap setting to be used, but still no higher than 140 knots.
There are no penalties, at least at my operator for an inoperative thrust reverser. The landing performance charts do not account for T/R usage when depicting required/actual landing distances. After touchdown, the stopping distance is based only on the drag from landing flaps, fully extended ground spoilers, and maximum braking.
6000 ft is roughly the minimum required runway length for an EMB-145 to be dispatched to at sea level (assuming a landing at max weight), increasing about 2% per thousand feet of elevation. A 15% correction factor must be applied for a contaminated runway, such as snow or rain. Actual landing distance is about 2/3 of that, so between 3500-4000 ft. That figure increases by 15% for a contaminated runway, an additional 15% for low visibility (less thn 3/4 SM
), and an additional 18% for a tailwind. Again, I can only vouch for procedues at the operator where I'm employed.