is it fine if I don’t remove my phone case whilst charging?

As a rule, yes, it's fine. You may need to be vigilant for a while if your case is from a dollar store or flea market. However, if the phone senses it is in danger of overheating, it will give you warning and it will shut itself down if you ignore the warning.

Yes, unless it hinders charging.

Pros:

1. You can charge as long as you want.
2. You can charge as many times as you want.
3. You can use while charging.
4. You cannot overcharge with Apple supplied cable and charger, it will auto switches OFF when full.

Cons:

1. Do not let it run below 20% too often
2. Do not let battery deplete too often.

You're welcome.