My thought on Nod's light units are they are all about taking risks. You risk that little bit of damage to your units every time you hit-and-run enemy vehicles/infantry/harvesters/whatever. The problem with buggies that they have far too much HP, combined with such a low cost, for that to be even determined "a risk to use in combat". I.e. the $300 loss for a buggy is basically nothing. Hence I think there should be a "higher risk and control" factor that involves a skill of using buggies effectively without wasting them, similarly to how poorly controlling bikes (usually involving infantry) will get you rekt. This leads onto my suggestion that if you halved (or even more of a nerf) buggy HP, they could still be dangerous IF they are controlled properly or if the enemy simply doesn't make an effort into dealing with them. That way using them isn't totally useless but it means that it takes more skill to use them and they are easier to fight against. The other advantage is it forces people to use other anti-infantry more (perhaps even an Arty or 2).
Comparing that to a $500 loss for a bike, which is still fairly small but can build up quickly, because GDI ARE capable of dealing with bikes significantly better than they are with buggies.
Light Tanks as I mentioned are not very good. I think that many Nod players forget that they are even there. There are some good things to use light tanks for, mostly cannon fodder and infantry squishing but they are still ok I guess. The problem with building light tanks (Prepare for RA-Style reasoning) is the time you've spent building that sluggish piece of junk, you could've built 2 buggies which go around trashing things instantly. A Light tank has the damage almost the same as a bike, except it costs $100 more, moves incredibly slowly and is easy to kill with most Anti-Armour fire. As I said, they are more a utility unit than an actual combat unit, which is sad.
If Light tanks did get a damage buff then I think there would be nothing wrong with giving bikes a small damage nerf (only a small one), as this would fit my "Risk strategies" theory better.
If anyone ever bothers to check out my RA mod (link in my signature), I made a different solution where the more "Nod-like" faction actually has no buggies, and their bikes are basically Armour-munching glass-cannons. I'm not suggesting removing buggies altogether (although its always a thought).
SSM, Arty and Rocket Launcher.
I agree SSM needs to have its requirements changed. Having thought about it, what would happen if the requirements for SSM and Rocket Launcher got swapped (including appropriate Rocket Launcher Buffs and making it GDI only)? Temple of Nod/Adv Comm are very late-game buildings, so I'd say it would be about the appropriate time for a Nod player to maybe need to break down or taunt a stubborn GDI player.
I would say if you changed SSM and Buffed the Rocket Launcher, could you not give Arty a minor buff too? It is powerful but VERY slow and an easy sitting duck. It might convince people that they are worth using every once in a while. (I use them on Obelisks a lot).
Flamers and Chem Warriors
I do agree that flamers are too powerful. I also agree that Chem Warriors are actually a nerfed version of flamers (for what people use flamers for) that require a temple to build, which is silly. Chem Warriors have a different warhead type, which has less infantry damage but more damage vs Armour types (Especially Light armour). Having these guys as an early-mid game unit would be quite a cool thing really. Flame Tanks however are fine, in fact they would be much better if you incorporated the buggy nerf into it.
In fact, why not make Infantry considerably cheaper to make? It makes them more viable without being overpowered, as it puts more pressure on players to use Anti-infantry weapons effectively.
When I made CW I did this, and I think infantry now have good balance. These pricings work quite well:
Bazookas: $150 or $200
Engineers: $600 (gotta protect them carefully).
Finally for apaches (based on what White told us recently), changing their warhead from HE to SA would probably work fine.