Hi Vijay,
For your question 1, refer to Nanda's answer above..I think there is a formula like ROUNDUP or ROUNDDOWN or CEIL or FLOOR..
For question 2, in the formula you have created, just revise it with this equation:
(DATE1 > 0) * ( (sy-datum - date1) / 365 ) + 0
OR
(DATE1 = 0) * 0 + ( (sy-datum - date1) / 365 )
Just choose between the two (2)..That formula will give you ZERO value if date1 is empty..
Regards,
Loed