Questions regarding perimeter drains, microtunnelling, etc.

What are the advantages/disadvantages of placing drain tile on top of the footer vs. next to the footing?
I ask as I am getting a lot of water under my basement the past couple of years and my sump pump runs much more frequently than it used to. Water is seeping into my sump pit via a rift which has been created just below point where the interior drain (from under my basement) is located. The point where the water is entering my sump pit is 8" below the floor of my basement. My perimeter drain is not connected to the sump pit, but rather to a drain pipe which daylights down a hill behind my house.
Of interest is the fact my perimeter drain does not appear to be capturing any appreciable water as there is not any flow out the end of the connected drain pipe. This drain pipe has adequate slope from the point it ties into the perimeter drain and I recently dug down to ensure the "tee" (perimeter drain to drain pipe) had not been compromised. It was in working order and when I ran a hose onto the exposed drain tile, the water did flow nicely out the drain pipe.
Is it possible that surface water is working its way under my footers and bypassing the drain tile (perhaps due to its location on top of the footers and not next to them)?
As noted earlier, the point where water is entering my sump pit is 8" below the floor. The drain tile (from the interior drain) is above this point. If I unplugged my sump pump, presumably allowing the water level to rise, would (should, actually) the interior drain below the basement floor and the exterior perimeter drain begin to capture the water (I understand the interior drain would feed water into the sump pit)? I believe the perimeter drain is above that 8" water entry point-- in its position on top of the footers.
The water table in my area is very high-- reportedly 19" higher than normal due to excessive precip over the past several months. My sump pump cycles more frequently after a heavy rain (once every ten minutes or so), peaking about 12-18 hours after the rain has ended and taking five or so days to return to a level where it might run once every 2-3 hours, assuming dry weather during this period. I wonder if I am partially a victim of excessively wet conditions at the moment or is there something else contributing?
My sump discharge is well away from the house and my gutter downspout extensions are buried and daylight 20'+ away. The grading around a couple of portions of the house is not the greatest, but I would have thought the perimeter drain would capture some/all of the surface water in these areas (back to my original question).
On a related note, I have considered the idea of having a pipe microtunneled from behind my property (large hill) under my foundation and connecting to the bottom of my sump pit. Assuming the technology is such that the tunneling accuracy would result in the pipe arriving at the bottom of my sump pit and not somewhere else, I can not think of any negatives associated with this strategy. It would daylight down a hill and the sump pump would then essentially serve as a safety valve in case a critter or something temporarily created a blockage in the hard pipe.
I appreciate any input related to the number of different things going on with my particular situation.
Thanks, --Howie
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