GOOGLEFINANCE – Get High & Low and Timestamp in Google Sheets

Just use the standard print dialog in Chrome (File -> Print / do not use the shortcut cmd+p, as this opens up a Google sheet specific print pop-up) and chose "save as PDF" (tried on a Mac/OSX). This exports the charts in a vector format. There is no need for a Chromium add-on.

To get the count of all timestamps (in column A) that refer to Monday between 7:00 and 8:00, use the query

=query(A1:A, "select count(A) where dayofweek(A) = 2 and hour(A) = 7 label count(A) ''")

This where clause can be combined with inequalities such as where A <= date '2015-12-31' to specify the date range.

Since you have a bunch of queries, you probably don't want to hardcode the day and hour numbers in each. For the hours, assuming the column B is the leftmost column your table, the following will work:

... and hour(A) = " & hour($B2) & " label ...

For the day of week, it's easiest to add a hidden helper row with numbers 2,3,4,5,6,7,1 corresponding to Monday, Tuesday, and so on till Sunday. Then refer to that row with

... where dayofweek(A) = " & C$3 & " and ...

One can also use a lookup table for this, or even cook-up a formula to put together a string with full date and parse it to extract weekday, but this is more work.