Hello GNOVAK
for the first question: add a data series to your chart. The series should have as many cells as there are days in your chart. Set the first cell to 0, leave the middle cells blank and set the last cell to your target value. You can do that by simply using
=Sheet2!A1
or where ever your target data is. Specify in your chart settings that empty cells should be plotted and connected with a line. This way, you'll see a line from day1 at zero to day30 at target.
I don't really understand your second question. As Cyberkiwi has suggested, post some data to work with. If need be, draw the chart with the drawing tools to illustrate what you want.
cheers, teylyn