Option 1. Polyline edit (PE)-> Join -> Select all poly lines -> Close
Option 2. Fillet -> Radius 0,0 -> Multiple -> Click the ends of all the polylines to join them together then either polyline edit -> close or open the properties panel and select close.
To measure area & perimeter either List (LI) and select the poly line then you can cut and paste the answers into another programme or you can select the line and it will all appear in the properties panel. GTG manager behind me ;P