Are they comfortable in hot weather? No, in my experience none are, particularly. No getting around that.

Do they ruin flow state? - No, but I wear them all the time so I'm used to them.

I wear these. They're reasonably-priced, heavy-duty, and butterfly-style so I can wear them over pants and don't have to take off my shoes to put them on or remove them. Also open at the back of the knee which helps a little with heat.

I prefer hard-shell for "slide" on concrete, but if you want to use yours for snowboarding as well, you may want soft/sleeve style pads so you can put them under your pants instead. Look for D30 or similar.

I prefer butterfly closure for both - easier and faster on/off in all conditions, and can be opened fully to sweat-dry.

For wrists I like these: they're made of moisture-wicking quick-dry fabric and mesh, so they're cooler to wear and dry faster (not only less stinky and gross, also makes them last longer) and they also have D30 in the palms, a hi-tech shock absorber that in theory may help minimize damage to your elbow/arm/shoulder/collarbone should you make the mistake of instinctively attempting to break your fall with your hands.

For kneepads I like these (note: the same company makes a couple different models of butterfly-closure knee pads, but these are the ones you want, the other ones rely more heavily on cheaper stretchy materials).

Get butterfly-style (not sleeve-style) if you want to wear them over pants.

Here's a cheap option, I had multiple pairs of these.

I now wear these - they're pricier but considerably better-made (they have a D30-like material in them for increased impact absorption, the hard caps are replaceable, and they have a little strip of a rubberlike material at the top that helps keep them from sliding down).

"Butterfly" is what they call pads that close like this; they aren't the closed "sleeve" style where you have to pull them on starting at your toes or fingers (which is a pain for knee pads, since you're probably wearing shoes).

I'm not clear on what is making your shin take so much abuse but I know it happens because a friend of mine has the same problem. He actually wears a soccer shinguard on his leading leg.

As far as knees, here's a reasonably-priced good option, and a pricey one. I used to use the first one, upgraded to the second one.