Puzzle Bobble

Puzzle 1:
You have 3 containers measuring 8 liters, 5 liters, and 3 liters. The 8 liter container is completely full with water. Your goal is to end up with 4 liters in the 8 liter and 5 liter containers (i.e. 8-0-0 to 4-4-0).

You can only use the containers and can pour one at the time. How would you do it? (Note: there are generally 2 ways: 7 steps or 8 steps)

Puzzle 2:
In a pond, there are waterlillies. In 24 hours, the number of waterlillies double in number. The pond would be completely full in 60 days.

How many days will it take for the pond to be half full?

Puzzle 3:
The following numbers are arranged in a particular order:

8 5 4 9 1 7 6 3 2 0

What is the order? (doesn't take a math genius really...)

Puzzle 4:
A patient has a tumor in his stomach. The only way they can remove it is by using a laser to burn it out. However, the tumor is surrounded by healthy tissue. If the laser is too intense, it will kill the tissue. However, if the laser isn't strong enough, the tumor will not be affected either. So what must we do to remove the tumor without harming the healthy tissue?

Note: You cannot cut the patient up or make him ingest anything.