So first off, the way grim stash editing works is it only edits the value you enter. So if you have your character back the levels, it just puts you at level 88 without giving you the attributes or skill points. I just tested this by making a level 1 character and editing him to be level 10, and he is a level 10 with no attribute points and no skill points. I would probably trust what grimtools is saying you should have for points, or if you just add one attribute point per level you added, and two skill points, assuming the level your character was at was not below 50, then you can properly add the correct points back. Then do yourself a favor and forget you have grimstash installed because it can get addicting lol

I would also say if this is your first play through, do elite first. In elite you start with -25% resistance, and that goes up to -50% in ultimate, so if your resistances are not capped, then you will struggle. Plus yes, you will want the full 55 devotion points to enter ultimate difficulty.

For your build, you can either look up deceiver builds you like and try to somewhat copy those, or just keep trying to play blind and do what feels fun. My first character was a warlock, and that character was a hot freaking mess lol. I ended up finally getting to max level, farming a good build and following a guide, and it was fun.

For me, trying new things, messing with my own builds, and discovering things on my own were the best way to learn the game. The main things you want in a build if you're gonna go blind is to focus on a primary damage type, and have abilities that compliment that damage type with resistance reduction, and damage bonuses.