The VG Resource

Most of the files seem to be in .bin, .sim and .dat file format (as you have said). Unfortunately that doesn't really help all that much, as they are pretty random file formats. Sometimes you are able to unpack the .bin files, but unfortunately for this game it doesn't seem to be the case. For future reference, here is the unpacking tool mentioned in the previous sentence.

The good news is that the textures seem to be perfectly rippable. In the "flmodel" and "mapdata" folders, you should see many more folders. Within those many folders you should see many files, with extensions such as .nsbca, .nsbma, .mdlr, .nsbmdbin, .nsbtxbin. The files you want are .nsbtxbin. From here you will need to extract the files, go to the folder they were extracted to, and drag the file onto this. This should decompress them, leaving new files, which you can drag onto this. (The basic gist of this is that the textures are decompressed, so you are uncompressing the files and extracting the textures from said file)

From there you should be able to see the textures that were in that file. Unfortunately I have never played Golden Sun: Dark Dawn, so I have no idea what each of those textures correspond to.

A good person to contact about this is MagicMaker or Barubary, as both seem to have specific knowledge on this game.

Unfortunately the same format as above, so I don't have much to say here... Contacting one of the people above will be your best bet. (I can say that the font should be in the "data>font" folder, though )

As far as other stuff from the game goes, with Tinke you can easily (although it may be a tedious process) rip the sound effects from this game, which would be in the "data>sound" file. If you don't wanna rip the sound effects (as there are quite a few), I suggest opening "test_data.sdat>STRM" as there are a bunch of cool-sounding stuff that can help the ripping process fly by.