I'm new to Illustrator and trying to create a line graph from info I've imported from an excel spreadsheet. The info contained in the graph reflects a study with samples at random intervals during the day over a 5 day period. The graph needs to show two sets of information on the left and right - 2 separate value axises to reflect two different sets of data (sort of like two graphs superimposed).
I have two problems.

First, if I edit the cells with quotation marks to change the date/times to values for the category axis, illustrator spaces them at regular intervals. Makes sense, but I'd like the bottom to show the days, and plot the points reflective of the hours of the sample.I could make categories for each hour, but the samples are taken at random times.

For example, the points are plotted at 8/20 2:11pm, 8/20 9:36 pm, 8/21 7:45am, etc.
I'd like to have the days spread out on the bottom of the graph and plot the points relative to the hours in the day but only show the dates at the bottom of the graph, for clarity's sake. Is there a template for time along that axis? I'd be grateful for some advice or a tutorial.

The second question is about how to add a second axis on the right side of the graph with different units than the left. I've looked through dozens of tutorials and am now playing with creating a new graph in a separate layer, but I'm a bit lost. Thanks in advance for your time and any advice.