Axle to crown. Measure from the dropout to the brake bolt on the back of the fork.
Brake drop. Measure from the brake bolt vertically to the centre of the brake pad fixing bolt. Under 49mm is standard 'race' clearance. 'Long drop' calipers up to 57mm.
Steerer diameter. Remove the stem cap and measure across the inside of the stem. For that fork to fit you're looking for 28/29mm.
Steerer length. New forks come with 250mm of steerer so will generally need shortening.
Headset crown race. Look carefully at the top & bottom of the head tube. If they are the same diameter then your crown race will fit that new fork.
Can we see some pictures of your bike? That would be helpful.
Luv'n'stuff
John.