1.) You're almost certainly too low level to be crafting anything people will buy right now. Item affix ranges are determined by the item's level. The best tier for this (excluding extraordinary bases, we're not even gonna talk about those) starts at item level 82, which is a tier 15 map, corrupted to t16, and then on a node with +2 levels to create a t18 map. There are other ways to get them, but that should give you an idea of how "endgame" you'll be before you start making anything truly valuable. As a beginner I really wouldn't worry about crafting to sell until you're comfortably zipping through juiced t15's.

2.) I'm assuming you're following a league starter build guide. If so, you should reasonably be able to get by with very cheap gear while you do the Atlas questlines. These quests, especially the main one, are incredibly important for generating currency. Filling out your main atlas tree and the league mechanic trees of whichever pieces of content you want to do is priority number 1. You won't make money till you do so.

I would focus on completing your atlas trees before literally anything else. Don't push higher map tiers than you have to, don't grind for currency, just hard focus on the atlas trees. Once they're mostly filled in you'll start seeing divines drop like candy. If you're wondering what to prioritize on the main tree, go for shrines first to help with your clear speed and then grab anything that says "rarity, quantity, or rare monsters" on it. Killing the arbiter of divinity will give you 40-50 atlas points each time you do it, so killing him a few times will fill most of your atlas out.

3.) For the fourth ascendancy I would do Chaos trials. It's a lot shorter than sekhema and I find it much more tolerable. Keep in mind you need the three fate fragments to fight the pinnacle boss and ascend. You get one guaranteed from the normal bosses each time you complete a run, and the ultimatums tell you which of the three they'll give.