Slope, Topographic Wetness Index

I am working on a project that requires me to extract values from rasters (viz the slope and TWI) for a set of point dataset that I have. I tried calculating the Slope, Flow accumulation and the TWI from the DEM (using ArcGIS 10.1) but somehow the slope and the TWI raster outputs seems erroneous! For slope, I get values ranging from 0 to 89 (file attached here) and for TWI, I get values between 19.58 and 9.40 (file attached), with no data data for most of the area! However, while extracting values for both slope and TWI to my point shape file, I mostly get 0 as the RASTERVALUE for most of the point data. Could anyone kindly review where exactly I am going wrong and how do I correctly get the slope and the TWI?