Onoff

Yes. No.

I've been doing it for 40 years. Even down to dipping thread ends in peelable "wax" to save cleaning concrete splashes out if the threads. A nut might help knock the burr off but you'll still end up with a sharp end without dressing. Most of my cut/dressed ends come up square and you wouldn't know them from a shop bought bolt.

I cut to length with a slitting disc then dress with a flap disc to slightly taper the end, remove any burr and clean the end up. Never put the nuts on first.

If you look at commercial stairs, the stringers are routed and the treads fit into them.

Doubt it, with loads of modern wood glue. You can buy proper stair jigs for doing exactly what I did. I also had 3 lengths of studding under the top, middle and bottom treads.

My stairs method was to make a jig and have the treads sat in a routed out housing. This is just a couple of tread section left over from the original tree house stairs. Glued and screwed, it was super strong:

Caw!

The Bionic visor options, all fit the same mask shell: Notes • PUL9601725N - Polycarbonate Clear Visor - Uncoated • PUL9601726P - Acetate Clear Visor - Anti-Mist/Scratch Resistant • PUL9601727Q - Polycarbonate Clear Visor - Anti-Fog/Scratch Resistant • PUL9601729S - Bionic shade 5 visor

I'd render the top of the wall with a water proof render, have a slight fall outward. I'd then stick the slate to that. A line of black CT1 between each slate. Also a ring of CT1 around your stud before you push the packing washer on.

I've two of these: https://www.zoro.co.uk/shop/personal-protection-and-clothing/full-face-protection-kits/1011623-bionic-face-shield-with-uncoated-visor/p/ZT1177444X?

In all seriousness you can get non misting visors for the Bionic mask. I invariably take my glasses off anyway when I'm cutting/grinding welding as I tend to work really close up. Judging by my welding I should perhaps put them back on...

More a case of matter stuck in mind... Most recent one I had was with a piece of thin stainless held in mole grips in my left hand. I was dressing it with a 1mm slitting disc holding the grinder in my right. Somehow the blade ripped the stainless out from the grips straight into my face shield. With plain goggles in it would have been my neck. Sobering!

The free version of nanoCAD is worth a look. If you're used to old style, 2D AutoCAD it's a doddle to get along with: https://nanocad.com/products/nanocad-free/

Slip some 1/4" thick plastic washers over the bolts before refixing the posts. That'll give a clearance and stop the staining.

You've got to be comfortable using an angle grinder to then get accurate. I only ever use one now wearing full face shield like a Honeywell Bionic after a few near misses through getting over confident and getting swarf hit me in the face/neck despite wearing normal goggles. A bandsaw is relatively slow and won't burn the paint off. It's like a powered hacksaw tbh. Also has fine teeth that shouldn't catch or rip the work.

DeWalt (which I know you love), do nice 18V portable bandsaws. The issue is they don't appear to come with a stand meaning you'd have to wield it freehand so to speak. 3rd party stands are available or you can DIY one. Without, then it lacks the versatility and accuracy of say my Sheppach 230V one. FEMI do one on a stand I do know.

Catch thin, unclamped metal with a big toothed blade and it can go horribly wrong. Ask me how I know, nearly lost a finger. I've known worse happen.

Idris?

Slowly dispose of it by wearing Great Escape trousers!

Are you @zoothorn in disguise by any chance?

https://www.toolstation.com/scheppach-mbs1100-1100w-127mm-metal-cutting-bandsaw-stand/p15189

I believe foxes take more rats than cats, at least if there aren't any leftover kebabs which are their natural foodstuff.

Travis Perkins, Selco etc are nationwide builders merchants as opposed to say B&Q, Homebase that are diy stores. You'll likely have an independent merchant near you.

I'm working on printing an adapter...don't wait up: Buy one if you want it quick: https://www.ebay.co.uk/itm/285050150261?