they are actually 16x16, but making the art out of sets of 4 pixels.
I think that the HD Patcher mod will support any resolution that your computer can actually load, although I think at odd resolutions (eg, 13x) would be buggy. a 128x128 canvas is totally supported by the patcher.
[OPTIMIZATION] Optimine v3 (FPS Boost) [1.2_02]
viewtopic.php?f=25&t=132717&hilit=optimine
[MOD] McRegion v5 (Optimized Saves) [1.2_02]
viewtopic.php?f=25&t=120160
They will boost your FPS a LOT. I went from 15 FPS on medium fog to 30+ with no fog.
I think that the HD Patcher mod will support any resolution that your computer can actually load, although I think at odd resolutions (eg, 13x) would be buggy. a 128x128 canvas is totally supported by the patcher.
Example of 8x