I saw someone's advice before that you should not set a loss limit, i.e. do not lose in any currency you buy and be patient until you gain from the currency or get your money back from the currency.

I saw advice from another person that diversifying currencies is a good thing as you do not put your money in one currency and lose everything.

I saw advice from another person saying buy the currency as soon as it goes down.

My first question: Here remains, are all these tips correct or wrong?

My second question: Is what I did in my portfolio good or wrong?

My third question: What is better, speculation or long-term investment?

My fourth question: How do I know if the currency will go up or down, and is selling when making a profit with a very small profit the solution or waiting for a longer time for the currency to rise more?

Please take a look at my portfolio and give me your advice