1. Is it possible to complete (or atleast to the point where development is currently at) the game without gaining any mental changes/corruption/lewdness or any of the lewd stats? If so, how?

2. If not, how do I minimize it? 

3. I've been hearing about this day of sloth event that makes the boss of the event stronger when past the 100th day. Should I be worried about that? Cause now I'm discouraged from rpg grinding normally. 

4. Lastly, the game defaults tap to confirm as off since I updated to 0.27.3. And everytime I run the game it reverts the settings back to off. Any ideas? 

1. Apparently it's possible to avoid mental changes and lewdness, it's called a "pure" run/playthrough and the NG+ room tracks a separate score for such playthroughs. Corruption though accumulates passively, and from a few sources like removing the collar and killing demons.

2. Mainly good time management, avoiding removing the collar and using Blessed Waters from the church. I haven't tried it, but it seems to be doable in Normal difficulty. Much harder than a lewd Normal run though.

3. Not an issue as long as you remove the barrier in the demonic domain in Mountainreach. There's a trick to it that leaves players stumped, check the wiki if you get stuck. After that, you can just use Star Knightess in the fight for an easy win.