First, I want to know the size of the community and if things like climbing the ladder and participating in community events matter. Is this site official to Pokémon in any way? And if not, is it large enough that you can earn money or does it at least have a decent amount of recognition? The site seems very large for just a Pokémon community, with all of the different topics, but before I get started, I just want to make sure if any of this is worth my time.
Smogon/Pokemon Showdown are not affiliated with TPC in any way. However, it is well-known enough in the general Pokemon community that even cartridge competitive battlers will use it for the purpose of teambuilding/testing. There are ~18K players online on Pokemon Showdown as of writing this, which is fairly normal.
There are a few major tournaments with cash prizes each year, and a number of smaller community-supported tournaments with small cash prizes. Other than that, the main reason to play is just for enjoyment or because you want to increase your skill. The Smogon forums are mainly focused around high-level competitive play, but there is a substantial casual playerbase on Pokemon Showdown.
Second, are there any resources for getting started with the different tiers? When I started playing chess, there were tons of resources to get me started, and I was able to go from a complete beginner to 1300 in about three months from playing the game. I want to know if there is anything similar for Pokémon Showdown/Smogon. Are there any resources to get me from a complete beginner to a decent ladder rating or skill level?
Each tier's subforum has a bunch of pinned threads containing information about the specific tier. The Metagame Discussion, Viability Ratings, and Sample Teams are probably the most helpful to new players.
This thread helps introduce concepts which are important to Singles competitive battling as a whole (though it is written for Gen 8, which has a different set of Pokemon and does not have the Terastal mechanic). There's another thread on battling concepts/terminology
here. There are probably some video guides (both official and unofficial) out there, but I can't find them right now.
Third, I want to know who the directors and staff of the site are, and if they can view things like my IP address and personal data. I also want to know if the site uses any trackers and if, or how, it sells any data I have. I have an ad blocker already, but I still want to know.
Staff and administrators are listed
here. Data/privacy information is listed
here.
For my last question, I want to know why I should use Pokémon Showdown and Smogon. What sets Smogon apart from other Pokémon communities and why should I choose to play on this site?
The goal of Smogon is to establish the tier system, in which each Pokemon is (more or less) ranked by its power level. Each Pokemon should be tiered with other Pokemon with around the same power level, so that there is always a place in which it is usable. Additionally, mechanics which revolve mostly around luck rather than skill (such as evasion moves and OHKO moves) are banned. In contrast, the official battle formats, BSS and VGC, only have a single tier (in which most Pokemon are not viable). Additionally, they restrict the pool of available Pokemon (somewhat) arbitrarily and do not ban moves or Pokemon for the sake of competitive balance.
However, official battle formats are also playable on Pokemon Showdown, and it has the benefit that the teambuilder lets you cut out all of the busywork related to breeding/resetting.