exit seats and load check please

currenlty booked on VS45 LHR-JFK on April 1 -taking my son to the Big Apple for an early 21st pressie.

Am i correct I can now buy exit row seats by calling the Fc now?
I have currently bagged 62 H & K -are these better than the extra leg room ? (never used them)
and better than exit row ? ( i am guessing not)
which exit row is better 39 or 49?

and lastly could someone please do a load check on 45 and also the earlier flight 003

many thanks

VS 45 J9 D9 R9 Z3 W9 S9 K9 Y9 B9 L9 M9 Q9 X9 N9 O0
VS 3 J9 D9 R9 Z0 W9 S8 K3 Y9 B9 L9 M9 Q9 X6 N0 O0

Sorry, can't advise on the seats

Regards
R3dV