Yes, from what I understand you can do some cool things with 20 CPU and to be clear you can exceed that in short-bursts with an overflow bucket of 10,000 (See: CPU Limit doc). The simulation to my knowledge from the site is also free, if you wanted to try it out first: (See Simulation).
As of writing, the live severs are:
Shard0: 5s a Tick
Shard1: 3.4s a Tick
Shard2: 3.2s a tick
Shard3: 3.6 a tick
Though that can vary, ~3 is average and decent for being able to respond to live-troubleshooting of code.
I've never read that review before now. I've visited slack a few times but only started jumping on more recently, while tight-nit I wouldn't call it toxic most players I see get help relatively quickly and questions are answered.
There are a few things I'd question about the post but I do not know the situation or what led up to it. I've only played with the private client a little, so couldn't help there.
this guy's review - I'll admit I normally do have Screeps up on another tab when playing other games to make sure code-behavior is acting correctly or to update the code as needed for things, though I'd view the game as a game about automation more than active-action unless your mid-attack. We'll have to see how Screeps Arena is.
This other one - Yep, there's a market for credits and Tokens similar to ISK and Plex in Eve-Online. Though you can play the market to get credits not just though selling tokens. There are two types of "Novice zones" a Novice Area in green which you need to have a Global Control Level (in-game-level) less than 3 to enter, and Respawn Zones that anyone can enter but you have to give up all your previous territory, not your account levels or code-base. Both zones are cut-off for an extended period of time from the outside world giving you time to prepare.
See: Starter Areas
In-fact if you haven't already I'd start reading the Docs Page and API Page Before I purchased I went though the Docs page several times to get an idea of the concepts.