You have most of this right, the stuff about turning off animations, not worrying about RAM and leaving cache files alone, etc. But I disagree a little with manually closing apps and worrying about background processes.
Most background processes are not really running, they're only inactive system processes. Meaning they're only cached in RAM, just kinda siting there, listening and waiting for something to happen that requires their use. For example, the keyboard. When you're not typing it just sits, parked in memory as a background process until you tap on the screen again.
The thing is, while background processes are parked in RAM they are using virtually no CPU cycles or power. Killing them or otherwise worrying about them is not only a waste of time, it's counter-productive because they will probably just reload anyway, wasting CPU cycles and power.
More importantly, you're not taking advantage of Android's optimization capabilities, resulting in less than optimal performance and reduced battery life. Android can learn from your usage habits and optimize itself to suit. It also learns when lag occurs or other system glitches and adjusts to cope with them better. It actually will run better and better as you use it. But it has to be allowed the chance to do so. If a user intervenes and manually closes apps or kills processes, the learning/optimization process is broken. The interventions essentially causes incorrect information to be sent to Android, ultimately degrading performance.
Best to simply use the phone, let Android do it's job as intended, relax and enjoy your phone. Don't worry, be happy.