Excel 2007 all MS updts

I have a line chart of y-axis values and x-axis dates. The both axes get
their data from the same Excel worksheet with the y-axis 'like temperatures'.
That is, values vary (oscillate from + to - and - to + back (but not
sinusoidal, just an oscillation back and forth around the y=0 line).

The issue is that the x-axis is displayed (vertically) with ALL the dates
overwriting each other for a 2 year period of time. All my data is daily
M-F. Hence, for the y=0 line ALL the daily dates are bunched up. These
dates then overlay the actual data.

1) I'd like the x-axis to be labeled on the x-axis not the y=0 axis.
2) What I'd like to do is to display the dates every week or month or
n-weeks (n being 1, 2, 3, 4 etc as I might visually want). How can I do this?
3) Also, is it possible to display the x and y values (coordinates) on
points of change of direction? Like when it goes from -20 and starts warming
up or it's at 50 and starts to cool down?
TIA!!
Seems simple but I can't seem to figure this out.