Don that cold front got me too. I had a brand new, really nice OS stave check on me even after splitting it in half. Normally in the summer I would lay my new debarked OS staves in a sleeping bag so they wouldn't dry so fast, for the first week or so. I neglected this and it got me.
This is a good learning project and its the best way to learn. It shows that there's a lot more to consistently making bows than some people think. I find it best to read the books on it, read the websites, then make a few bows, then read again. You just can't get what you need to be good from reading alone.
So if you screw something up on a stave or bow then don't just give up on it, use it to practice other techniques on, ie. handle wraps, stain, heat bending, heat treating, etc.
The checking is somewhat normal and usually insignificant but if the check runs off the side it might need to be dealt with. Otherwise, CA and move on.
The reflex on your stave is relatively insignificant. If, during the tillering or steaming, it disappeared, I would just treat it as though it never existed. Don't try to get it back.
Especially since your dealing with other problems on this one.
When you steam you need to let the bow dry out for at least a few days before working it again.
Pics would help on your tillering issue.