Just managed to do blue science... A few questions

Right so... No screenshots yet as I've not figured out how to shot the whole stupid spaghetti thing.

When I say spaghetti I mean... It's ridiculous. Everything is retrofitted and bodged in as an afterthought, BUT...

I've got a rudimentary line of blue science going. Managed to research lots of blue stuff.

My questions:

1. Does deleting already existing construction become easier? I've just built new factories spaghetti-ing off my OG coal/iron feeds to try new methods or automate one particular thing for that moment etc etc. when can I mass delete and rebuild easily?? I'm not the quickest with mouse, and certainly not as fast as Nilaus I been watching.

2. I've researched and made the belt immunity thing and put it in my equipment grid of my modular armour. Why am I still being yeeted around by belts?!