How to determine the number of ez track links needed for HO layout

[cowboyin1954]

I am new to this but want to buy the Durango &Silverton set.  It has ez track but I need to buy additional pieces.  My area is wall to wall 176" x 113".  The set should have my corners covered and some of the straight lines.  How many more straight pieces do I need.  Also do I need to run a power wire with several jumps to the track for even power and if so do I need special equipment to attach the power to the track?