Well the more things I watch about it it almost seems better on your computer then on a box. Do you know the post numbers for your best ones.
At the get go, I recommended an inexpensive PC .. yes, it's more work, but it will blow a box away .. period .. I use an i3 with HDMI out that cost me $90.00 on a dell.com refurb clearance .. it works flawlessly and that's all I use it for .. thus, I don't have to worry about it being compromised ..
These boxes are very much dependent on the user ..
KODI is an open source freeware, much like LINUX .. it comes pretty much bare bones on a download whether it's Google Play, etc .. KODI was originally written for the X-Box One, it was called XBMC and it was designed as a Home Theater interface, which was morphed for use with a Home Theater PC .. to hold and store music, pictures, Netflix access, etc .. it is a totally legit software, just like LINUX is totally legit .. the Addons have no affiliation with the KODI team ..
I run a bandwidth meter periodically, and nothing I have streamed over KODI has used more than 10Mbps, most much less since many of these things are highly compressed .. my Netfix uses 9 ..
You are still overthinking this and, BTW, are you reading all the posts .. ?? We've covered much of it ..