I think with term of trading, you should start from one particular coin, probably from Bitcoin or Ethereum, if you will attend to hold, it is better to start with 3 to 5 different, but top coins as well.
I think that it is best to start with 1K, then spend them on the scheme 50/25/25, and first it is desirable to choose the top tokens that would minimize the risks. The income will be small, but with minimal risks.
Yes you are right. It is necessary to invest in different coins and it is better to invest immediately in good coins, such as ETH or BTC.