I was initially in favor of the GA, particularly because of all the yelling at you I do about civic changes. That siad, I've since changed my mind. People have made excellent points about waiting until you have more pop, more land, and a more established place. That said, I'm also kind of in favor of changing civics right now. A few things to think about: while in anarchy, you will lose less money. You will also have time to either capture more cities or pillage more tile improvements. Also, a golden age now will increase its cost later.
I think a golden age will be great, once you get a GP farm set up. GA, revolt to pacifism, CS, etc, and you'll have a +200% GP generation for ~10 turns. Revolt out of pacifism at the end of it (keep CS if needed) and enjoy having generated lots of GP points for those turns. You can even starve your GP farm during this period to further increase your points; 10 turns of starvation, if carefully planned (count food in the stockpile) will be survivable. The perfect time for this, to me, looks like after you finish off HC.
Militarily, I'd finish off HC. First, do not keep all his cities. Burn most of them, keeping only the ones most productive and most necessary to outline his lands, allowing you to back-fill once your economy gets back on its feet. I'd think about building a small number of new units, but mostly I'd focus on quality over quantity. What I mean is as follows; you'll be able to kill HC pretty easily now. Just do that. (DO NOT FORGET TO PILLAGE THE IMPROVEMENTS AROUND CITIES YOU ARE GOING TO RAZE-it's extra cash you absolutely need.) Your next war will be, tautologically, either defensive or offensive. In the period where you're rebuilding your economy, you need to prep for the defensive war. I think instead of keeping your power rating high, aim to keep it at about half your near rivals, maybe less, particularly as you make friends with someone with lots of power. Check Aelf's EMC threads for his power graphs to get an idea of what's okay. At the same time, use your military not for garrison duties on the border, but instead for forming a mobile reserve on the border, so that you can annihilate an enemy stack which attacks you, like you did with HC. By the time you're preparing for your next offensive war, your economy will be back on its feet and you'll be set to spam units like Shaka was meant to do.
For the GP you have right now. I'd settle them or build academies. As has previously been discussed, lightbulbing Philosophy isn't that helpful. It gets you further along the liberalism path...but as we talked about in the pre-game that isn't as big a deal with Shaka, and I think a settled GP or academy will give you more benefit in the long term. Also, you can't trade Philo around as much. Bulbing it eventually might make sense, (particularly with no tech brokering) but right now you don't have many people to trade it to. Also, the idea that you want another AI to get the religion is really important. That would be huge, as it will select your next victim for you.
Also, watch out for Hang Kon. He's been a tricky little bugger in my games; he's good at teching and also not terribly reliable as a friend. That said, maybe he'll be good to you. You are Shaka, after all.