chart format - ssrs 2008

The stored procedure returns fields i.e. field1, field2, etc...
field1 has figures in percentages such as:
3.65, -1.22, 1.3, etc...
field2 has the dates.
On the horizontal axis line, the dates are shown correctly.
On the vertical axis of the chart, it shows the percentage figues.
These percentage figures have +ve and -ve values and there is 0 in the middle of the vertical axis.
All working fine...
Questions
1-
How do I show the percentage % sign next to these numbers on the vertical axis?
2-
How can I move the labels of the dates to the centre of the chart where it crosses the horizontal 0 line ?
Thankyou