A:AnswerIt does imrpove the battery, but not to much since iphone 7 and 7 plus doesn’t support officially fast chargin for those models i would recommend the 12w charger it’s cheaper and would give u almos the same spped of charging that is better than the 5w charger that comes in the box with the iphone
A:AnswerDepends on the adapter your device has. If it's a lightning adapter, then you need a USB-C to Lightning. If it's one of the new iPad Pros then a straight USB-C will work. At least one end needs to be USB-C though to work with this charger. Then it's a matter of how long you'd like it to be. I tend to go for the 2 meter/6.6 foot cables just for that extra bit of length and usability. I'll link the choices below for you. Otherwise their 1 meter/3.3 foot options will work just fine as well.