Memory speed is important! ? Answered
On your section on memory you didn't really cover SD card speed which is really important, particularly if you are going to take videos. Smartphones are now able to record 4K videos but even HD videos require more than "just a SD card".
I use a HTC U11 smartphone which is capable of recording video at 60fps and the new Sony XZ smartphone can capture at over 900fps! I have found one needs at least a U3 (indicated by a '3' inside the 'U' on the SD card) rated card.
There are a lot of fake cards out there and I get mine from Amazon and always ensure they state that they are "Despatched from and sold by Amazon" (usually stated somewhere around the 'add to basket' button). This usually means it was supplied to Amazon by a reputable source.