This can all be done with JSL as well, but will require some manual coding (except for the summary table, which generates a script upon running, saved to the data table scripts under "Source"). Do you have experience with JSL scripting or general programming? If not, I would recommend reading through the JSL Scripting Guide, which is available under Help > Books > Scripting Guide
To get you started, here's how I would get rid of the blank rows (blank values in a column named "TEST")
dt = Current Data Table();
dt << select where(:Test == "");
dt << delete rows;
This exact same code could be used to delete rows in which a column has the keywords you wish to select for, for instance, looking for the string "Useless Data" :
dt = Current Data Table();
dt << select where(:Test == "Useless Data");
dt << delete rows;
To change a column data type, you can use the following code (this references a column named "Test")
dt:Test << Data type( Numeric ) << Set Modeling Type( Continuous );
I hope this helps!
Julian