Inside of a package called
custom content essentials on the vault there is a file I've found useful that you might consider for your resource section. It's a spreadsheet that details what every entry in every 2da file is for. The spreadsheet file is (unsurprisingly) called 2da.xls.
I am surprised that you haven't got
paint.net on your list as I find that it compliments the gimp. There are things that easier to do in one package than the other and vice-versa.
Personally I don't use 2da editors/ set editors etc. As these are plain text files I tend use a text editor for such things. One of the best (if not
the best) that I have found is
notepad++. Actually I find it has more uses than I've already mentioned such as hacking/editing the ASCII versions of models.
For combining 2 2da files I've found that
winmerge is very usefull as it's simply a matter of comparing the 2 2da files in winmerge and copying the entries that you want from one side to the other.
Hope that you find this helpful.
TR