I’m light as a feather, yet the strongest person can’t hold me for five minutes. What am I?

What does the following BrainBat signifies?

ABCDEFGHIJKLMNOPQRSTUVWYZ

QQQQQQQQQQQQQQQQQQQQQQQQQ.

I know there are two methods by using three time the same number with a plus(+) operator , you can make sum as 60.

One of them is 20+20+20.

whats the other way ?

I make two people out of one. What am I?

What demands an answer, but asks no questions

What has many keys but can’t open a single lock?

You may enter, but you may not come in. I have space, but no room. I have keys, but open no lock. What am I?

Without looking at a calendar, within a minute name, a boy's name using 5 consecutive 1st letters of 5 consecutive months

I have a head like a cat and feet like a cat, but I am not a cat. What am I?

I am under you when I am whole.
I shift above you if you remove the first letter.
I come all around you if you remove the second as well.

Can you tell me who I am?