To translate you'll need:
Dslazy. (for rom unpack)
not really. The main thing you need is ndstool, which is also what DSlazy and the other tools use. I also prefer DSbuff, as it has more functions. However, Crystaltile2 can extract the files inside of a rom.
Tiled 2002 (for Sprites/graphics)
Again, not really. There is a tool called Tile Molester, which also works great, but Crystaltile2 works the best overall. And you'll also need a graphic editing software, and I suggest you use photoshop.
Crystaltile2 is the best for viewing graphics, as graphics of the DS are not always 8x8/16x16. You can input custom sizes in Crystaltile2, with many other options, as you can apply maps, rotations, inverses, bite jumps, etc
However, you can't seriously be doing the graphic related jobs in these pixel by pixel editors- you'll need to export the image and use an actual editor such as gimp or photoshop to edit, and import it back, which also CT2 supports.
crystaltile2 (for hex editing.)
and other tools depending if the game has files in archives...
best of luck
-opearn