Hi

Topspeed - If you compare the F16 vs F-16XL both with F-100-pw-200 engines the F-16 has a higher top speed. Why, I can't tell you.

Manueverability - Yes, the Mirage 2000 is a Delta winged airplane and not a poor dogfighter at all. I would however pick an F-16 any day in a dogfight. The Delta winged Mirage 2000 has a higher instantaneous turn rate, but a lower sustained. The advantage in instantaneous turn rate is not enough to get a missile of the rail during the first 180 degree of turn (Neutral merge), so what really counts in a dogfight between the two is sustained turn rate.

Payload - Yes, you were right

Speed is always a hard one to compare since it all depends on altitude, temperature etc.