The "difficulty" manages to have one block built not faster than in 10 minutes in average. It helps to avoid collisions. If we decrease the difficulty to have 1 block in 10 seconds instead of current 10 minutes, we would have way more collisions, and the blocks we mine will have higher chance to be discarded.

What can be a solution for a decentralized pool of nodes around the world? May be already invented but I am not aware?

let me start
 - some have smart contracts which allow to create "tokens" like erc-20
 - some allow anonymous transactions which hide the recipient's wallet address

what else?

I am trying to find if some alt coins have cool features I am not aware of.

Guys I am not sure if this is the right place for these questions. anyway

These questions about modern, new crypto currencies as Doge, Shiba, etc.

Do they normally have dedicated eco system being peer-to-peer payment system, have their server pools, like Bitcoin network? Or these "coins" are some kind abstractions, "tokens" which just can be traded on crypto exchanges?

How do the new cryptos which work like bitcoin with their network and proof-of-work, protect from an attack of someone who has significantly higher CPU power (pool of servers), who can re-do the proof-of-work rebuilding the block chain in the attacker favor?

Do the first coins appear from mining first blocks, or there are first transactions with some kind of initial deposits?