Quickly Solve this riddle

7 - 4 + 3 * 0 + 1 = ?

A professor thinks of two consecutive numbers between 1 and 10.
'A' knows the 1st number and 'B' knows the second number

A: I do not know your number.
B: Nor do I know your number.
A: Now I know.

What are the four solutions for this?

Name a key which is hardest to turn.

What can jump higher than a building?

What makes this number unique: 8,549,176,320?

12345 a famous South Indian actor
567 is a path in jumbled form
8 & 10 are same letters
9 is one among the first six alphabets.
WHO AM I?

What four weights can be used to balance from 1 to 30 pounds?

what one word does the below rebus identifies?

What word begins and ends with an E, but has only one letter?

John was going on a jungle trip. He asked his wife to pack something to eat, something to drink and something to burn if he feels cold in the jungle. When John opens the backpack he found just one thing in the bag. What was it?