I skimmed through the original posts, and I feel like [Part 5] interests me the most, discussion-wise.
To the fiest point, about characters with community ties... You don't need to kill off everyone your character would care about before they set off on an adventure. In general, a person would need an extremely important reason to just leave.
For me personally, having a wife and children, I wouldn't leave to cross the world for the sake of adventure. But, I would help a neighbor or friend go track an animal they shot. Or help them get their vehicle out of a ditch. For a low level adventurer, these are perfectly acceptable challenges.
As a DM you can weave in story elements that may make characters feel invested in, and obligated to, see the work completed. Say, while tracking a deer, another neighbor is waylaid by goblins and kidnapped. The adventurer just escalated, and most people won't leave their neighbor to their fate.
As a final thought on this one: a level 1 or 2character isn't leaving their live behind at the drop of a hat, but a series of escalating "right time, right place" or "you're the only one that can" situations can do a lot to grt that character out the door and into the story.
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To the second point: min/maxing doesn't preclude roleplaying. Everyone wants to be good at their job, and handicapping yourself doesn't make you more interesting. If you hire a plumber, you want someone that is good at it, not someone that has dabbled in plumbing/teaching/assembly line work/auto mechanic/ostrich jockeying/etc.
A similar idea occurs with adventurers. Classes are abstracts, mostly. A wizard may call themselves a wizard, as there is a lot of in-game baggage thag goes with it. But a rogue can be a scout, spy, thief, acrobat, pirate, etc., and likely wont ever refer to themselves as a "rogue" in character.
A cleric can be a priest, acolyte, servant, faithful, missionary... you get it.
So say you want to make a character that wants to hit stuff really hard with an axe. You'll probably go fighter or barbarian. You'll focus on strength and con, and maybe boost dexterity. You've already min/maxed. Is your character less for having done so? Absolutely not. If you treat your character only as a bundle of numbers, your roleplay will suffer, and the character will fall flat. But if Ungthir, Blade Champion of Gruumsh is a little dumb and unwise because he swings an axe harder than any other half-orc in the village, fine. What you make of the numbers is what's important, not the numbers themselves. BUT, you can't sacrifice the ability to be effective at your role and call it great characterization.