Manipulating Date/Time/Value tables

[stadleybear]

Hi everyone. I'm struggling with this one.
Referring to the 'Sample File' I am trying to derive a table of data from a source table that:
Combines separate row (date) and column (time) values into a single excel format timestamp, and return the values associate with that date/time
Another function would be to sum the values (for say different time intervals, 15 min, 30 min etc.) to derive a table of hourly values for each day.
The source table could be quite a large data set (15 min values for every day for several years) so I'm thinking an array formula would be best?.
I'd like to understand the solution so an explanation would be greatly appreciated.

Thanks you all in advance :D