Awesome, I use FL10 as well, so I can be kind of, sort of helpful
If you're looking for actual chiptune synths (as opposed to "chiptune styled", which can be quite different), I have a couple of suggestions: first is magical8bit. It's free, and all the waveforms are sampled directly from the NES, plus you get an easy to use amplitude envelope. The other resource I use quite often is Adventure Kid Waveforms. These are again sampled directly from the NES, and aside from the fantastic 8 bit waveforms, there's a plethora of other great waveforms you can plug in to the 3x Osc (which is how I did a ton of my synthesis for a while), or Toxic Biohazard (how I do the bulk of my synthesis now), or Harmless, or Sytrus, or... you get the idea, FL/Image-Line have a VERY wide selection of hugely customizable synths to choose from.
So, drums. They sound pushed pretty far back into the soundscape. I think they could be brought up further without detracting from the rest of it fairly easily. How are you with EQ and compression? Also, drum selection is going to be important.. I think in this case, a kick with some more bite (meaning more audible attack, and more in the higher freqs as opposed to just lows) would be more appropriate, and the snare could use some more punch (meaning a bit more in the low freqs; most snares typically have a sweet spot somewhere in the 300-650 hz range, which should be pretty easy to see if you slap a "Fruity Parametric EQ 2" on there). My drum chain usually looks like this:
Fruity Parametric EQ 2
Compression (I HIGHLY recommend BLOCKFISH, which is part of the Fish Filet Series you can get for free here)
Fruity Blood Overdrive (just default on the OD does the trick to fatten up the freq spectrum a bit)
I'll delve just a bit into the other instrumentation, but I think I've given you enough to chew on for a bit. The square arp reminds me of the GM squarewave that Finale uses (which I have a love/hate relationship with, the instruments being under the "hate" category), and so I personally don't like it. I'd go with a delayed pluck square (which you can make in m8b really easily; low sustain, no attack, tiny bit of decay), and then for the held notes, plug a 3x Osc into the same mixer track with the Adventure Kid sampled NES squarewave. This way, the two will sound cohesive together, but they'll have a distinct characteristic.
The bass instrument could be brought forward as well without affecting other stuff much, you can look at the EQing on the low frequencies (although it does help it cut if there's a bit in the highs)
As I'm listening through again, I think the mixing could be more carefully handled as well. Everything seems to be kinda fighting for my attention, and I'm not sure what you WANT me to be paying attention to. Things like lower volume + stereo separation on arps will make sure they're still heard without fighting other stuff for attention (I'd also recommend some reverb and slight delay for fuller saturation). Just listen to what you think should be up front and what doesn't NEED to be consciously heard. Bring things up and push things back as needed, and this'll be sounding a ton better in no time.
I really like all your interpretations, and I'd like to see this pushed further! Feel free to PM me if you have any other questions. Good luck