All my answers are listed below your questions in Italicized font:
1. How long can Pycon hold their breath? I theorize this is comparable to a human?
It is exactly the same length as a Human can without training. Even though we do not have lungs we still have to breathe.2. Can Pycon swim, or do rivers/streams pose a great challenge to them?
We can swim. It isn't fun though being waterlogged, however our shape can be altered: Air bubble bloating or shaping ourselves to be a boat shape is very helpful.3. Do Pycon have the scent of clay, and if so what sort of predators do you think they would have to contend with?
We smell of clay... Predators? Not many that I know of eat clay... However, we are small and some of us wear gemstone fashion which an attact critters that would enjoy shiny objects: Foxes, Racoons, Maybe even birds if we glitter enough. Bit other wise, pretty much what Nivel said.4. Would Yukmen treat them any differently?
Pfft. Nope.5. Is clay as ubiquitous in Mizahar as it is in the real world?
Nivel answer this one well.6. Is 'unpure' clay disgusting or unhealthy to Pycon?
Unpure clay sounds like mud... However, clay is pretty subjective to the Pycon taste wise and effect wise if it contains more of one thing than another.7. How can I tell how strong a Pycon is? Are they comparable to a human, or would it be based off their weight?
It actually has a rough idea of how strong a Pycon is in the Lore... Let me go find them. There are a few quotes.
It may look solid enough, but it will not withstand moderate or heavy hits - a person stepping on them will easily squash their bodies, revealing that they have no blood, bones or internal organs.
A Pycon's clay flesh can be fully controlled, stretched, turned and twisted as long as it is attached to the head or nexus. It can also be reattached to the main body if separated, provided that this happens within a couple hours. Every part of a Pycon's body can be used as a joint, though unnatural motions require some concentration on their part. The peculiar anatomy of the Pycon makes them surprisingly durable despite their fragile bodies; they often escape danger by playing dead and keeping their heads safe.
As you can read from those quotes, they are pretty durable and strong. I wouldn't say that their strength is derived from one thing or another. However, clay is a heavy dense material to begin with and most, if no all, of our physical strength comes from our elasticity or ability to mold.8. Pycon have elastic bodies, is there a comparison to this elasticity? I'm sort of imagining soft clay that bounces back to the original position unless it gets crushed too badly.
I imagined something sort of like soft clay, maybe more like playdoh or molding clay. I always imagine tension that a Pycon creates acts much like a rubberband down after you pull it out and then release it. Nivel mentione da few skills in her answer to 7 which I didn't mention above because I feel they are more reflective to this answer. Pyken is a Pycon specific style of Unarmed Combat that Pycons use their elasticity, weight, and ability to unattach and reattach limbs to combat against others. Acrobatics takes our ability to be flexible and elasticity to a whole other level of insanity though, I think Archailist would be best to answer that though personally.
Our size is not a laughing matter after all
We are truly beasts in the battlefield.