Commander is often considered the main casual format of Magic the Gathering, and it is one of my favorite two formats to play. As Rezzahan said, it is a 100-card singleton format where your deck is built around a legendary creature. The format allows nearly every card in the game, with the exception of a very small banlist.
You can find the rules here: https://mtgcommander.net/index.php/rules/.
You can find content on lots of youtube channels, including these (just organized alphabetically, not by quality): The Command Zone, Commander's Quarters, EDH Deckbuilding, EDHRECast, The Eddi-H Channel, Jumbo Commander, Tolarian Community College.
I do need to one minor correction to the previous answer.
Starting life in Commander is 40, not 25.Quote from Rezzahan »The games start with 25 life
In some formats, a deck is 60 cards. For draft, it's 40. Most constructed formats (Standard, Modern, Pioneer, Legacy, etc), it's 60. Commander is 100. Prismatic is 250 cards.Lightning Bolt but each with a different name.[quote from="Vaindioux1 »" url="/forums/magic-fundamentals/magic-general/823976-noob-with-dumb-questions-be-ready?comment=1"]3)What is drafting? Lots of cheap lots on Ebay are advertised as "Great for drafting".[/card]Draft is a format where you select cards from a random pool, build a deck, and play it against others.
- Booster draft uses sealed booster packs - you pay at the beginning, and you keeps cards after the draft.
- Cube draft is different - one person curates a collection of cards intended to be drafted together. When everyone sits down to draft, they are given randomized "boosters" and draft just like a booster draft. There is no cost to play, and at the end of the draft, all the cards go back into the cube. This is my other favorite format to play, and I have four cubes, each designed to deliver an entirely different play experience. The best part is that you can do away with filler cards - in booster packs, the majority of cards are not actually cards you want to play, so you will often open a packs and maybe want 1-3 cards from it, while in cube you often have to make much more nuanced decisions because there will be several cards you really don't want to pass to your opponents.[quote from="Vaindioux1 »" url="/forums/magic-fundamentals/magic-general/823976-noob-with-dumb-questions-be-ready?comment=1"]4)60 cards are a deck right? I don't understand much about these cards but can't a player just grab the most powerful cards in the game and kick ass?
Rezzahan gave a great answer here:
Once you've determined what format you are playing, you build a deck according to the rules of the format (what sets are allowed, what cards are banned, how many copies are allowed (singleton vs playsets of four vs draft, where you can play as many copies as you pull)), you need to build a deck that functions cohesively. You need a plan to win, and you need a way to prevent your opponents from winning. Is your deck aggro? Control? Combo?Quote from Rezzahan »It's a pile. A deck has an actual plan, how to win the game, how not to lose the game, what to do early on, what to do later, how to deal with what the opponent is presenting, etc.
As far as cramming all the most powerful cards into a deck, you might do well, but Magic is rarely a game of brute force. The way cards interact is more subtle, more strategic. Card synergy is important, even when you aren't trying to build a game-winning combo. What if one powerful card shuts down your other powerful card? I remember playing at a store 0over 15 years ago, where there was a guy with a deck running 7 of the Power 9 (considered by some to be the most powerful cards ever printed). I was playing decks worth $10-20, And he never won a single game. A pile of powerful cards, but with no good synergy or plan to win, is almost always inferior to a well-crafted deck that maximizes the power of its cards through a focused plan.
That depends on what format you are playing. Booster drafts often play only one set. But most constructed formats allow cards from various sets to be mixed. Standard allows somewhere around 5-8 sets to be mixed. Modern allows all the main sets since Eighth Edition to be mixed (so approximately 18 years worth of cards at this point). And Commander allows cards from the entire length of the game to be mixed (something like over 20,000 cards).
Core sets are considered more beginner friendly and often contain a higher percentage of reprints (there was a time when they were 100% reprints, but those days are fortunately behind us).
A 30 card promo deck sounds like the new player decks they used to give out for free. New players could get two of them from a store and mix them together for a two color 60-card beginner deck. They were 100% reprints and often contained weaker or simpler cards just to get the player to understand the basics of the game.
The best way to find good deals is to first figure out what you are trying to get. Are you playing a particular format? Or just collecting to have them in a binder? For example, if you want to play Standard, buying older cards will just waste money, while if you want to play Commander, buying all standard cards will limit your power level severely. If you are just collecting, buying bulk with 50 copies each of draft chaff (the cards no one would play outside of draft) will limit you to lots of copies of terrible cards and no copies of good cards.
Start with a plan. What format will you play? Or what collection are you trying to build (like complete sets or one of every dragon)? Only then can you figure out the most financially efficient way to accomplish your goals.
Opportunity cost. Each color has an identity and strategies to accompany it. They each have strengths and weaknesses, and you choose which ones you want to work with. Want them all at the same time? Now you have to juggle the ability to produce the right colors to cast the various spells. A mono-color deck should never have color issues, but it will suffer from the color's weaknesses - for example, a red deck can burn down the opponents quickly, but it can't deal with their enchantments. Two-color decks allow you to combine the strengths and hopefully one will overlap over the weaknesses of the other, but you start to worry about having the right color at the right time. The color pie is useful to know. And some colors will just fit your preferred playstyle more than others.
Again, this is format dependent. A 60-card deck running 20 lands and 4 copies each of 10 cards will play very consistently; each game will go generally like the last one. A 100-card singleton Commander deck could play a dozen games and not see the same cards; each game will be a somewhat unique experience. Are you looking for more of the same or a more varied experience?
Unless the card used to remove something says to exile it, they generally go to the graveyard. But don't think of the graveyard as a dead-end - many decks have ways to use the graveyard as another resource. Black reanimation decks are the most common example, but others exist based on mechanics or card abilities.