bank2budget in excel

Hello excel world

I hope this is the correct place to ask this, if not please point me to where I should post it.

I would like some pointers and help to create a bank2budget spreadsheet, consisting of:-
1. creating a list for categorizing spend (data validation) - understand this one
2. import cvs bank statements - understand this
This is where I need help
3. Combining bank statements - call then BankA CreidtCardB & CreditCardC
a) they are slightly different layouts, and I want to map/merge them all into an all transactions statement (masterStatement) - how do you map/merge in excel
b) if I add Februarys transactions to BankA January, automatically to update the all transactions statement (masterStatement)
4. Add a column to the masterStatement to categorizing the spend
5. From the all transactions statement (masterStatement) create a pivot table, categories on the y-axis and total spend on the x-axis.
6. And do this on a month by month basis, I also want to interleave some column with the pivot tables to be able to assign a budget to each category of spend, and have a balance on each category as the year goes on.

I have found a spread sheet (TS102601457.xltx - had to zip it to TS102601457.zip as the uploader didn't like the .xltx) that does most of this but want to understand how it does it. What is the best way to reverse engineer it? I have found the formula auditing but it appears quite basic.

I have started my spreadsheet moneymonitors_bank2budget.v4.xlsx to show the idea but a long way to go :-)

Kind regards
Giles