First, did you write all those lore explanations yourself? If so, I am impressed. I really like your system, and the explanations make sense. I particularly like the increase in shell count for all autocannons, as it brings it more in line with lore specifications for autocannons.
That said, I do have a few suggestions to improve on this system:
I would add the ability to shoot the C-Gauss at any point during the charge, with damage scaled accordingly, similar to the bombast laser. Maybe give it Light Gauss damage with no extra charge (given the tonnages), and full damage with full charge, with the damage increase frontloaded, to correspond to the charging characteristics of capacitors (see graph in the link below). C-Gauss would automatically fire at full charge (think Spartan Laser), to dissipate energy from the capacitors without damaging them.
http://www.learninga...rging-graph.png
At first, I thought the Clan and IS ERMLs were improperly balanced (Clan ERML is indisputably better than IS ERML), but after giving it thought, I agree with your values. IS should have inferior ER technology, because they are new to that, so their focus should be on the non-ER lasers. If they want to try to mimic the Clans’ strengths, they won’t do it as well.
I really like that PPCs have a charge time, as that does line up with lore behavior.
I think the best way to balance heat sinks is to buff IS single heat sinks a bit. With Clan double heat sink technology as good as it was, they saw no need to invest time into improving the single heat sink, while the Inner Sphere had only the single heat sink for a long time, resulting in a more efficient (say, maybe 25% as a starting value) single heat sink for the Inner Sphere, as compared to the Clans. Double heat sinks are equally efficient, but IS DHS are bulkier, due to the fact that it is a new, unrefined technology for the Inner Sphere. Set all DHS values to be 2 dissipation after fully skilled (i.e. proper maintenance to maintain full functionality).
Final comment, on the energy draw system. I would make the Gauss and PPC affect the energy draw where they would actually be drawing the energy. The PPC would draw energy while it is charging up to fire, and the Gauss would draw energy as it recharges its capacitors. The Clan gauss would draw energy as it charges up to fire and as it recharges its capacitors.
Overall, I really, really like your balance changes, and I would LOVE to see them in a public test server, hopefully getting rolled into the game eventually. My only fear is that PGI would destroy this system, too, with endless tweaks to eliminate the distinction between IS and Clan.