Clipping in and not killing myself

you will get used to it.

I clip in first right foot and then left and when clipping out I go left first. Just practice it on grass and you will be fine. I think when you try to unclip and nothing happens the panic sets in. I notice a good few riders will clip out well in advance of stopping and that might help as well.

anyway good luck with it

As above, practice the twisting motion or whatever movement it is with bike stationary.

where it can get tricky is if you have to stop suddenly and your focus is on braking and once the momentum stops it can be tricky as you need to decide which side you want to drop the leg

Lots of practice at junctions in a housing estate or on paths in a park. Keo pedals/cleats are cheap and widely available

For what it's worth I would suggest you try dual sided mountain bike pedals with multirelease SPD cleats. Dual sided pedals means it's pretty much always possible to clip in easily and the multirelease cleats are much easier to unclip. MTB shoes typically have recessed cleats so you can also walk around more easily. Sure for really long spins SPD-SL and Look pedals are more comfortable but as a star I reckon you can't go wrong with the MTB ones. He're what I am talking about:

The pedals: https://www.cyclesuperstore.ie/shop/pc/viewPrd.asp?idproduct=97320

The cleats: https://www.cyclesuperstore.ie/shop/pc/viewPrd.asp?idproduct=4248

I try to unclip my standing foot as I approach a stop if I can, like 2-3 wheel rotations away.

I'm a left leg unclip first rider which works fine in Ireland as you'll generally fall towards the verge but I live in a drive/ride on right hand side country at the moment and I always tell myself I should try to change.

You will fall occasionally, either through being distracted, or equipment malfunction or something. In the US a couple years ago, the screws of my cleat came loose and I only had one left holding it to the shoe, so what happened then was the cleat rotated as I turned my foot and so over I went. That was while in traffic, stopped at lights and so I fell in to traffic in front of a car. There were a few blown horns but thankfully nothing more serious happened, but it did scare me how helpless I felt when I realized I could not get the foot out.

Been using SPD-SL red cleats for years as I love the almost complete absence of float. Never had an issue unclipping, however a new set on for the last few weeks and I'm noticing both feet noticeably harder to unclip now. Nothing changed on the pedals, is there a setting on the cleat itself?

Change 'em every 3-6 months so this is maybe the 10th set in a row and the first time I've had any sense of an issue. Might be an ever so small design flaw perhaps.