For 3D modelling it used to be that a good multi-core CPU was more significant, but I'm guessing since GPUs are more a thing it probably has gone in that direction, (unless it hasn't).
I don't know what a good CPU is anymore either. Whatever you get you'll probably get all your caches hacked anyway.
Lightroom since v5 is bloated shite however much memory you have.
The free alternatives are slowly improving - none of them are good enough yet, but hoping it wont be too long before they're viable.
An m.2?
I considered one of those but the connector being underneath the motherboard was too much faff so I got a regular 2.5" SATA. Just realised I'm not sure if there's anything in the case to mount it though, probably need a 3.5" bracket. Arse.
So, no brackets, tape, nor dangling necessary. :)