Hi William, welcome to the Splinterlands!

I'll answer the questions you asked and then add a little info that may be useful for a new player

1. You need the Spellbook to access the crypto and NFT earning in the game
2. If you want to build your card deck through rewards and increase your crypto holding in the game you must have a spellbook
3. This question is difficult to answer simply as there are many ways to "play" the game, but I will firstly mention the obvious. The aim of the game is to play your cards against an opponent and to beat them. Winnin in the game will give you different things. It will increase your rank, top leaderboard players get prizes every season ( 2 week seasons), but to be at the top you need a max level deck, so that may be a goal to work towards. Each battle you win you also gain two oter things, a crypto called SPS , which is the games token ( more about that later) and Glint which you can spend in the shop for new reward cards
4. No, no surveys, its a genuine game that has been running since 2018, it is technically a Trading Card Game and the cards are NFT's

Some additional info:, The philisophy of the game is to be a true blockchain game, eventually everything will be decentralised and run on chain, meaning that the SPS holders will "own" and control the game direction. SPS is the governance token for the |SPS DAO, and each SPS represents a vote in DAO decisions, so more SPS ( it must be staked in the game) the more vote power ( like Hive).

Your share of the prize pool that you get for each win is determined by how much SPS you have staked in the game, so without any SPS staked you get no SPS rewards. Staked SPS also rewards you with more SPS daily and some vouchers ( vouchers can be sold in the game after Sept 3rd).

If you do not hold enough SPS to boost your win reward, you can rent SPS from other players who have surplus via an in-game rental market.

You can also rent cards to play with vis an in-game rental market, but there are good third party sited for that too like PeakMonsters.

There is another currency in game Dark Energy Crystals ( DEC) , these are used to buy cards, you can also buy cards with credits ( purchased via paypal etc, via in-game).

You can use BeeSwap to exchange tokens, or Hive Engine to buy DEC or SPS and transfer in-game via the game interface ( you can also transfer out too via the same interface).

If you buy the Spellbook, you also get 3,000 credits ( worth $3), these you can use to either buy cards, or better still rent cards (renting cards costs a fraction of buying cost).

As you increase in the ranks ( gain rating from wins) you will earn more SPS and Glint per battle, but you will earn SPS ONLY if you have staked SPS in-game or if you are renting somebody else's staked SPS

Hope that helps.

Final tip, if you buy the spell book, use that to rent cards from the Chaos Legion set, these are the cheapest and will progress you until you figure things out. One final thing, the level of your summoner determines what level of monster it can play, so make sure your summoner level is high enough to summon any monster you rent, or it will come into battle at a lower level to match your summoners "summoning level". To start with maybe level 4 Chaos legion Rare summoners and level 2 legendary summoners are a good intro. Rental period is a minimum of two days so try for the minimum first. A summoners stat table will tell you the level of different rarity cards it can summon