To be simple about what you have asked. Spot trading is just as simple as buy and hodl. The usual hodling of a coin either in your wallet or an exchange. You are suppose to buy low and wait to sell at your convenience on higher price. Here you don't lose the unit of your coin. That the unit of coin you bought is not lost only the value changes for higher or lower

Future trading include derivatives too. This is where real trading happens. You can lose your money. It is more risky. You buy or sell, you need a stop loss to avoid running out of balance.

Leverage is borrowed asset, money or coin to support your future trading. If you over borrow, it is risky. Sometimes 1-2 leverage or 1-1 ratio is better.

I think stop limit and stop loss are the same. Stop loss is simply to set a range to prevent your losses. Hope this can help you.