Questions on Destiny 2

A few questions about the game:

• Umbral Engrams. I find it weird that we are bombarded with these constantly yet we can only decode them after doing contact which is lvl 990 content.
• It seems I've reached a lvl cap of ~1000 on the gear I'm getting.
• How do I obtain upgrade modules?
• Aside from dismantling Legendary gear (which I just found out I can get by increasing reputation with different NPCs), is there a better way to obtain Legendary shards?
• Any advice on an up-to-date website for reference? Some type wiki for example. Many times I look up for answers and I get an article from 2018 that is totally outdated.
• I play on PS4. Anyone has a group I can join and try Raids with?