Hello, it seems you forgot to attach the files you were referring to. I am just okay with excel, but what you are intending to achieve seems straight forward, here is how I would approach the problem.
To compare two cells, I would use a formula on the row just to the right to determine the percentage. If number is less than hundred, then it's a decrease, if greater than hundred, then its an increase. I then use the if function to check for increases and decrease, and use filters to format the increasing and decreasing cells.
With regards to the rest of your brief, I can't really understand what you are trying to do without seeing a sample file. If I am considered for this job, I would like to see the files in question before I commit, thank you very much.