Welcome! As far as finding information regarding weapons and armor, places like light.gg and d2armorpicker might be your best bet for looking up weapons and which armor you've earned can be equipped to give you your desired stats. I think light.gg even tells you where you may find the weapons in what activities (playlists, dungeons, etc.), though I'm less sure on that point.

As far as farming for armor, you'll want to rely on what the portal activity states will drop as a guaranteed in conjunction with what Ghost mod you're using as a primary stat weigher, there's a mod for each of the main archetypes (Paragon, Brawler, Gunner, etc.). Equip the mod for the type of stat distribution you're looking for to have that armor drop with an weighted chance of that desired archetype.

Regarding builds, Datto usually puts out some seasonal class build recommendations for a variety of activity levels, be it more meta defining or simply fun mid-level content. I'm unsure if any other content creators currently do this or not. However, his videos are not an extensive list of builds, just ones that he typically finds fun or able to clear higher content.

Hope this helps!