Spot trading is highly risky, leverage traiding is more risky, future type of leverage trading is riskiest. Trading is risky, not like the way you depicted it good. Especially, newbies in trading do lose while experienced traders still have some chances to still lose.
1st of all i would like to say its very easy to use exchange.
No. Learning is required.
Trading of coin very simple and easy.
To learn, it can be simple, but to make use of it to gain is hard. That is why some people like to hold than trade, because many people still lose while trading.
Right now phemex allowed only trading 12-13 pairs on spot trading and 15-16 pairs in contract trading.
Binance will give you more. Check lists of exchanges according to their marketcap on Coinmarketcap, the ones at the top with highest marketcap have users that do lend for leverage trading, and these exchanges have more pairs. Especially Binance which is the first has more than 30 cryptocurrencies or more for future trading and many more for spot.