Modify existing MT5 script

The attached script (mq5 file) has its origins from https://www.earnforex.com/blog/forex-hourly-statistics-for-major-currency-pairs/

It simply prints out (saved as .csv) the average hourly pips of a pair for the last "n" bars, expressed as hour 0 to 23 (24 total), GMT adjusted.

I have three simple requests:-

1.) Instead of selected the previous "n" bars, I'd rather have a start and end date so I can research a historic date range.

2.) At the moment it only prints the pips per hour, but I also want to see the average pips per 15min within a day i.e. that would be 96 averages. That will probably require the script to be a separate file from the hourly pip one, that is fine.

3.) GMT adjustment is irrelevant to me, so that input can be removed, I am making these DST adjustments on my spreadsheet. It should simply start at the beginning of the daily divider (ctrl-y). That is 0:00 in forex, but it can get complicated when looking at an index e.g. US30 which starts at 1:00 and ends at hour 23:00 (see pic below), some other indexes only trade 18 hours. So that means the script should establish how many hours are between the dividers for the specific pair/index, then simply print out the average pips for the specific bars over the specified date range. So 24 in forex and 23 here for US30. (for 15min it would be 96(fx) and 92(us30)).

Note: the "PipsMultiplier" (100 for JPY pairs and 10000 for others) will have to remain as an input parameter as I like to adjust my points/pips' decimal place according to sensitivity of some symbols.