Also to move my drying across the house I have pulled the 10/3 electrical wire into the attack to drop into the new wall only to find out it is not long enough. Will I need to run a new length to the breaker box so tha I have a "home run" to the drier or is it okay to have a junction in the attic to feed the drier. The 10/3 is on a 30 amp breaker

You can extend using a junction box and cover plate, with cable connectors for the #10-3 cable and leave in it the attic. As long as the box will be accessible.