A:AnswerHP uses plastic for cases in this line of economy priced laptops. Fortunately I think their hinge covers are far more substantial and durable than other brands. I have a very similar HP and highly recommend it.
A:AnswerNo. Most modern normal use don't. You'll need an external based drive for most computers going forward as they use to much space and power on laptops. Or at least that's the excuse.
A:AnswerAccording to the Maintenance Guide at the HP website, this model system will have 2 internal DDR4-3200 memory slots but only supports 16GB, 12GB, or 8GB configuration TOTAL. It ships as 16GB with 1 module installed, but would run faster in dual channel mode with 2x 8GB modules instead. Unfortunately (as is the case with all modern laptops) changing RAM requires a significant disassembly of the case down to motherboard level. I have a recent similar HP system and highly recommend it.