yes
too much water will generally prevent oxygen from reaching the roots, they will then die and the rest of the plant will follow
Yes, both can.
yes, because with too much water, it is harder for the plant to get oxygen, thus, 'drowning' the plant
yes, water is important for plant growth. It provides nutrients for the plant, but too much water causes turgor pressure and that means that the plant's cells swell up. This is why too much water can kill a plant. Not enough water causes the plant's cells to shrink which can also cause death.
Too much water and it will become root-bound ... the ground surrounding the plant will get moldy and then stricken the plant with diseases. Don't think a plant can get too much sunlight ... there's a difference between "sunlight" and "full sun". Sunlight is somewhat diffused.
it dies
The plant either had too much or too little water or sunlight.
This depends on the type of plant you are growing. The obvious answer is enough but that may not help. Err on the dry side if in doubt.
well if you put too much the plant will get all clogged up which causes the plant to die
If a plant's soil has too much water, the roots can rot, and the plant can't get enough oxygen from the soil. If there is not enough water for a plant, the nutrients it needs cannot travel through the plant.
marijuana
Underwatering a plant will cause it to die because it won't get enough water to be supported. Overwatering will lead the plant to drown. And yes, it is possible for a plant to drown.