Hey, you have to remember, we've all been there!!
1) I use a 45mm. When I start getting drag I'll use this little sharpener gadget that I got. Its a blue circle and it'll sharpen my blades for me to get some more use out of. Actually, someone posted a really nice blade sharpener at Nancy Notions that I'm really interested in. You just run your blade through it and it sharpens it.
http://www.nancysnotions.com/product...e+sharpener.do
2) for handquilting I use a between size 10. This seems for me a good size.
You need to realize that in some circumstance what may be good for me, won't be good for you. Sometimes its just trial and error to find out what works for you.