What does the below rebus riddle means?

using four eights (8) and a one (1) and one mathematical symbol , create the number 100

If you're 8 feet away from a door and with each move you advance half the distance to the door. How many moves will it take to reach the door?

A cricket has 6 legs, a squirrel has 4 legs and a spider has 8 legs.

In a local zoo, it was found that the total number of legs is 612. Also, there are equal number of each of the above animals/insects.

Can you find out how many animals are there in the zoo?

Can it be possible to build a house that has all its four walls facing towards the South?

Find the number of squares in the below picture

Count The number of F's in the paragraph below:

"FINISHED FILES ARE THE RESULT OF YEARS OF SCIENTIFIC STUDY COMBINED WITH THE EXPERIENCE OF YEARS"

What goes up but never comes down?

Can you find the ages of a son, father and grandfather based on the following facts?
The sum of the ages of grandfather, father and son is 140 years.
The age of the son in months is the same as the grandfather in years.
The age of the son in days is the same as the father in weeks.

Until it is measured, not known. Yet how you miss it when it has gone. What is it?