Some serious basic physics lesson is required, you've got 5 volts on the output, and 1.2 am, that's 6 watts, with 2.4 amps, that's 12 watts, where is this 100 watt or 200 watt non-sense come from?
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You clearly have no idea how electricity works, not to mention 50 amp, the little wires in our phone can barely handle 10 amp of current, 1 milllion amps would destroy the little iPhone into a piece of charcoal. For electricity and being dangerous, current is far more important than voltage. Your everyday static is thousands of volts, but dissipate minuscule of current for a tiny amount of time, you can easily survive that. At 50 amps, even at 5Volts, will give you a jolt you will not soon forget, if not kill in the process.
So in short, a current over 3 amp will most likely destroy your iphone's charging circuit, a 50 amp will light it on fire, and 1 million amps will reduce it into a pile of dust.
Power dissipation is calculated as current x voltage, and voltage is current x resistance (or impedance in complex phasor terms). So effectivly, power dissipated is current^2 x resistance, since your device's charging circuit's input resistance is relative fixed, the thing that really drives the power dissipation IS the current. A device design to use 1 mp that is subjected to 50 amps will receive 2500 x more power than it's designed to handle, you tell me how much it will be destroyed. Stay in school and learn some physics.
So lets come back, since the phone has a fixed input resistance, what's going to result in a 50 amp current, well if 5 volt input gives you 1 amp, then an input of 250 volts will give you ~ 50 amps, so subjecting the phone to a 250V DC input will put 50 amps into the phone and instantly destroy it. Well in theory, the control circuit in the front end of the iphone charging system should prevent the iphone from taking higher current IF the input voltage stays at 5v. It 's correct it's irrelevant what the max current the supply can handle, as long as the input voltage is regulated not to exceed 5 volts, but that's not what you said, you stated 50 amp will not destroy the phone, which is a laughable concept, because it clearly can and 100% will. But I bet you a supply capable of 50 amp (or a mllion amp as you so smartly mention) would have so much capacitance that it would inveritably change the impedance of the iphone's charging circuit, and will produce undesirable impact to the phone. That's why manufacturers recommend to use the included charger for your phone to charge your phone, because those little "wall wart" chargers are not all made the same.
[doublepost=1497641433][/doublepost]I think the answer to this question is depends on what you define as "fast charging". There marketing term "fast charging" in most android phone refer to the phone's charging chipset's capability to negotiate a higher input voltage from a compatible charger that will allow a higher input current at an higher input voltage which would dissipate more power at a considerable more rapid pace into the lithium cell. Lithium battery charge regulation is a current control process, which means the cells are charge controlled via a regulated current while the cell voltage varies depends on the amount of charge being put into the cell. A fast charging phone (use Samsung galaxy line as an example) mated with a "rapid charge" charger would actually negotiate an input charge voltage of 9 volts, this would allow the input current to be ~ 2x more than the 5 v input voltage, with a 2x input current, the power dissipation is then 2^2 =4 times the normal rate, so the battery is charge very fast. However, this charging current is only allowed when the lithium cell is relatively depleted (which mean the cell voltage is no where close to its rated max). That is why "fast charge" a phone works by allowing you to charge from 10 or 20% to 75% at a very fast rate. But to fully charge a lithium cell, the input current have to be carefully controlled otherwise the cell would leak and explode, that's why even with rapid charge the last 10-20% of the battery is charged no faster even with a "fast charger".
With iPhone, even up to iPhone 6s, full rapid charging (which is a capability directly support by Qualcom chipsets) is not available (since iPhones don't use Qualcomm chipsets). iPhones can't negotiate a higher initial input voltage like the high end android phones can. However, with newer iPhones, the maximum input current allowed by the charging circuit during the lower to middle charging curve (below 75% for instance) is increased because new iPhone are getting bigger batteries where the charging current limits would present a long charge time undesirable from a marketing perspective, that's why the new iPhone would charge faster when used with an iPad charger which could supply 2 amps at 5 volts vs. the 1amp at 5 volts of a regular iPhone charger.
HOWEVER, as a word of advice, one of the key ways to stress a lithium battery is to subject it to strong current while charging. A stronger current stresses the cells and reduce the charge cycle in the long run, that is also why many "rapid charging" android phones batteries tends to deteriorate faster than iPhones. Apple made a conscious decision to slow down iphone battery charging to extend the battery longevity in the long run. Feel free to "fast charge" our iphone, but do so knowing it may negatively impact the overall battery longevity.
My word of advice would be charge the iphone with the charge it comes with at the slower rate if you can afford the time, use a fast charger only when absolutely required. There is no free lunch.
Now the final drum roll, the iPhone SE, per my observation, absolutely the iPhone SE is capable of drawing more than 1 amp when charging if the charging adapter is capable of supplying that current (presumably because it uses similar innards as the iPhone 6s), however, there's little reason to push the little iPhone with more current considering how small the battery is, the benefit of getting the middle charge curve to proceed faster on such a small battery really doesn't offset the reduced longevity on the battery in the long run. It really doesn't take that long to charge the SE even with the regular iPhone charger.
So in a nutshell, iPhone SE will charge a bit faster with an iPad (or any 5 volt charger capable of supply 2 amp current), but it will do so at a bit of penalty to the long term battery longevity, now do what you need with full awareness of the physics behind the scene.
