A:AnswerI was looking at that model as well. What you have listed is exactly the only difference. You are pretty much paying $100 more for a 1TB SSD instead of a 512 SSD. IS the extra $100 it worth it? In my opinion no, but you do save the "hassle" of having to buy another SSD, opening up the laptop and installing it yourself.
A:AnswerSpecifications list 4 cell which is the 90W battery. If you see 3 cell, it is 48W. Been researching the heck out of the Asus Tuft A15 on various websites.
A:AnswerYes, this machine can support an additional M.2 drive and a single 2.5" storage drive. https://dlcdnets.asus.com/pub/ASUS/GamingNB/FA506IH/E16601_FA506_FA706_Upgrade_Guide_V2_WEB.pdf