Water level should be 2-3 inches above skimmer lip or edge. Usually about 3" 75mm or at least 1/2 way up the mouth of the skimmer. however this depends on the strength of suction from the pump. so long as there is no air being sucked into the system is the first rule to keep in mind. the second is the faster the water is moving as it goes into the skimmer the better. If you have a floating suction-side skimmer about 3/16 to 1/2" or 10 to 15 mm or more depending on pump strength.
It won't work as a skimmer if your water level is above the skimmer. If you watch how the skimmer works, the water is pulled in over the skimmer door and it won't "skim" the floating debris off the surface of the water if the water level covers the entire opening, your skimmer will just suck in water that is below the surface. If you keep the water level so it's at least below the opening an inch or so, you should be o.k. If you've recently had alot of rain, you may need to drain some water out of the pool so your skimmers function properly.
The water level needs to be maintained at the middle of the skimmer opening or center of the tile line.
Just enough so that the skimmer is above the water and the pipes to the filter and filter can be drained.
If you have a top skimmer basket the water level should be at least an inch above the basket, so you are not sucking any air. They seem to operate more effectivly at removing floating material BEFORE IT SINKS if the level is about half the distance from the top to the bottom of the skimmer opening.
The water will spill out through the skimmer, unless the skimmer it is blocked. Otherwise, it will spill over the top. It should not hurt the pool.
Ideally you show keep your water level between one third and one half the way up the opening of the skimmer. This is the level at which the skimmer(s) operate most efficiently.
Yes it can be too full. If the water level is above the center of the skimmer opening, the skimmers will not function propely and the pools surface will collect debris.
No you just have to get the water level below the skimmer after that you should have no trouble making repairs.
Regardless of the position of any tiles on the pool wall The water level should be about 3 or 4 inches / 75-100mm above the top of the skimmer vein before the skimmer basket or at such a level that it does not suck air through the skimmer. of you have a suction side floating pool skimmer you can let it get as high as you like and as long as it is sealed properly as low as you like.
turn the pool pump off,take off the cover of the pool skimmer box, The pool water level must be above the area where the skimmer box meets the pool wall. If it is not, add water to the pool until it is at least 1 inch above this seam.
That depends on the type of skimmer in ground or above ground and from what material it is made, The water is leaking between gaskets