Ahh, didn't know about not being able to bloom them.
As for the svarts, there are a few things you can do with them. Whatever you do, don't chop forests, as that free 1 hammer makes them much better than anything else you can do. In addition, following FoL will allow you to have all those forests give +1 food, so your real problem is going to be the happy cap. As such, aside from food resources, its usually not best to build farms unless absolutely necessary, and never chop down a forest to do it. Also, if you run agrarianism, don't plant farms under forests if you can help it, and switch out to something else once you have FoL.
After the early game, there are two important things to remember. First, your mages are illusionists. That means that everything that they summon will be an illusion. An illusion can't kill something, it can only damage it up to 90%. This is when attacking. I'm not sure, but it may be able to kill while defending. In addition to this, after winning a round of combat, the illusion is healed completely. The second thing to remember is that assasins are recon units, and therefore benefit from sinister. That means that instead of being attack 5, defense 3 +1 poison, they are attack 6 defense 3 +1 poison, and can get another +1 poison from nature 2. This means that with 1 nature 2 mage, you can have an army of attack 8 defense 5 units who attack the weakest unit in the stack. They do have -50% city strength, but because strength is additive in civ, getting combat 1-3 would leave you with +60% strength in the field and +10% in cities, making combat ideal promotions to take. In addition, taking something like shock will guarantee that they attack weak melee units, making them even more useful. Add powerful assasins and illusions, and you should have NO illusions about what tech path to take. In addition to all of this, your rangers will be attack 8, defense 7, +1 poison from nature 2. As for satyr's, I have never actually found them to be useful, but if you find otherwise go ahead and play with them.
As for druids, well, if you want them, grab them, if you don't oh well. It won't make or break your game. FoL vs CoE is another up to you thing. You'll still be able to bloom if you don't risk your priests in combat after switching, but you will loose the ability to generate more ancient forests. On the other hand, all CoE gives you is gibbon and shadowriders. If you want to use shadowriders, this may be worth it. Otherwise, there is no real reason to switch.