In my opinion, (and I know what's up) from extensive personal experience is that Samsung's are as good as any other battery available right now. Sonys aren't much better, if at all. Grab at least 2 of those, any of the above mentioned chargers, and don't be scared to use the charging cable for the Sigelei.
If your tank is getting very hot, I bet you're using a .2 coil. Try the next higher ohm coil that's available for that tank. (.5?) It will run cooler and your battery life will be significantly better.
I wasted a long time rebuilding and I strongly feel that prebuilt coils are 95% as good as building your own. In fact, I believe prebuilts are better for subtanks. Sure they cost money, but rebuilding supplies cost money too, it makes a mess, and I have much better things to do with my time. (like reading this forum endlessly)
My words of advise to you is to take small steps. The setup you'll have within a week will be fantastic and wasting time and money chasing the next best thing won't greatly benefit your vaping experience. I've spent thousands, and in the end my preferred setup is almost identical to what you're buying now. It was worth it though, I'm so glad I don't smoke butts anymore.