Form 16 A

Dear experts,

       I have some doubt on TDS certificate my questions are....

1. wht is the due date for issuing TDS certificate after deducting TDS?

2. If we don't issue TDS certificate with in due date then wht will happn?

3. wht is diifrenc between form16 and form 16A and on whch cases we have to issue form 16 and 16A.?

4. From whch date TDS changings will be applicable like ...UTN, yearly once E-tds returns,etc....?

Thank you...

PRASAD