Bisqued clay is definately not as strong as high-fired stoneware, but I've been playing with them for years with no issues. The only problem I can see is because they're porous if they freeze while water-soaked it will destroy them. But I've moved them around, picked them up in many different ways.
The bisque looks like pumice rock (almost).
As for making your own ,definately go for it, I buy premixed clay online, probably $25.00 shipped. Roll out with rolling pin, newspaper inside for support, cover with plastic to slow drying to prevent cracking.
In theory one could fire piece in a bonfire or something like that, that's a little unpredictable but if you get the piece to glow its definately fired enough!
The whole process is a lot of fun!
I'll post some other pieces when I get time...