[ASAP]

Having worked with excel for 10+ years... All you need to learn is the following-

Pivot Tables
Vlookups
Sumifs
Concatenate

And a few other "if statements"... if it can't be done with one of those or a combination of those, chances are extremely high you are over complicating it. My biggest issue with getting too advanced in Excel is getting Excel to do things it's not really meant for... which is what many companies strive for because they are cheap and won't spend money for proper tools.

The 2nd issue is ; writing mile long formulas is something that should be left for a "BI" or Business Analytics team not for a Finance Manager... plus if I was interested in writing mile long formulas, I'd be a SW engineer making way more money.