2. Doesn't it have a threading dial? If so, then you can disengage the half-nut and move the carriage back, being sure to re-engage at the same setting on the threading dial. Otherwise, you turn off the spindle at the end of the thread, retract the tool a few thou, then turn it back on in reverse to move back to the start of the thread.
3. 0.0015" runout it pretty darned good for out of the box! If you want better than that, you'll probably need to use a 4-jaw chuck.