Bamboo Fleece Qs

I bought some bamboo fleece, and it's wonderfully soft and stretchy!

Now I want to turn it into diapers. I know I use the Ball Needle on my machine for stretchy materials. What sort of thread should I use? At our local craft stores they have the all-purpose 100% cotton and the heavy 100% cotton. Are either of these good, or should I order some thread online somewhere?

Also I am turning and top-stitching them. I assume I use a zigzag stitch when sewing the pieces together, then a straight stitch for top-stiching.

I also was wondering if my machine's overlocking stitches are sufficient to "overlock" the inserts, or if I should just turn and top-stitch those as well.

And the last question, which side of the fleece should touch baby's skin, the fleecy side or the knit side? The fleece is wonderful and soft, but I'd think the diapers would be more durable if the knit side faced out.

Thanks in advance!

Ball needle or stretch needle will be perfect.
Thread, I use a regular all purpose thread and have had no problems so far.
for T&T I would use a straight stitch for sewing together and for top stitching, you need the straight stitch holding them together to get a neat edge, you could use the zig-zag stitch as well but it shouldn't be necessary except in the elastic areas as zig-zag works better for elastic.
You will have to see how your machine is for the overlocking stitch, some work fine others don't, just remember to trim your corners (if you have any) if you end up T&T them or they will be a nightmare to topstitch.
I prefer the knit side of the fleece to be touching the baby, it is smoother and seems to wash better this way, have you pre-washed the fabric? the texture of the fleece side can change quite a bit after washing and the fabric will shrink a bit too so if you don't pre-wash you might find the nappy doesn't fit as well after washing.
HTH

Thanks so so much for all of that! I think I'll give my overlocking stitches a whirl on some scrap bits and wash em and see how they do. The fabric is supposed to be pre-shrunk but I'll probably give it a wash anyway... The last time I ordered pre-shrunk it shrunk more in the wash!

I've also read about stretching the fabric a bit as you sew so that the stitches don't snap when you stretch the fabric later. I figured I'd orient the fabric so the most stretch is sideways for fastening the nappy.

stretch going sideways is right, don't stretch too much when sewing as you could end up with baggy stitches.
If you have a walking foot I'd recommend using it as it makes life so much easier when working with thicker or stretchy fabrics.