Yep, still around. Mostly lurking around since I'm mostly playing through some other games that I've neglected. And yep, remember you from the Chaos Legion boards. I really should replay that, but I don't know if I want to do maintenance on my console/controllers, or just emulate it.
TLR /is/ a good game, but it's not one I would recommend to just anyone. My friend is still a bit sore that I beat a certain boss fight that was plaguing him for weeks just by rearranging his team and casually blowing through it. Granted, I suggested the game to him as more of a torture test. It's more in line with the SaGa series, which can be rather obtuse.
The game already gives you the tools to break it from the start; it only takes a little bit before (12 units) or after (15 units) a major boss fight to snap the difficulty in half, and can be done within 3 hours or so. Although that's assuming you have the right union compositions to make it go fast(er), and it's not the best against certain bosses that operate as massive dps checks.
You've already got the right idea with BR being the main factor that influences various things. There's a more technical explanation of how BR EXP is calculated on the wiki, but for the most part, you just want to keep things within 30 Turns and maybe allow your units to get KO'd. It's a bit of strategy and resource management to really get the most out of the system. You don't have to go to the lengths some of us do to get through the game; we just happen to like optimizing our parties and sometimes our own goals/restrictions require us to more strictly map out how everything develops. Plus, some of our behaviours are holdovers from the X360 version, which was just plain nasty with the BR EXP multipliers.
And to go back to your "doing better in battle" question: for me, doing well in a battle is getting 25+ KOs, ending on Turn 30, while making sure that I maximize the number of units using arts per Turn. Or at least as close to that as possible. The game "punishes" me by giving me a lower BR EXP gain due to my "poor" performance. But you don't need that level of optimization to get through the game. Just paying attention to how your units are growing and not letting BR get out of control (more difficult on PC/PS4/SWI) should be enough.