You certianly can switch to the Options, just be sure you use the same size needle tips that you are using with the plastic ones. There really shouldn’t be all that much difference and if the tote is going to be felted it really dosen’t matter at all!
Well one thing that could be a problem is that your gauge may change. We tend to knit differently with different slickness of the needles. If you don’t think it’ll be a problem or you want to do a gauge swatch with the new needles to check, you can continue knitting by knitting onto the new needles. Example: hold new needle in right hand old needle in left hand and go on and knit.
Yup! You just hold the plastic circ in your left hand, Options in the right and knit all the stitches onto the Options. When the plastic circ is empty just knit with the options!
The Options are the best needles out there, fixed or interchangeable. Or maybe the Addi’s. I really think they’re equal, though. (This is just my opinion)