ignored import file lines
This is very difficult to answer without sample data.  Your data may contain carriage returns, or not escape quotation marks properly.  However, if you can't safely share the data, here are some troubleshooting steps:


Try uploading to a demo server (demo.civicrm.org) to ensure you're seeing the same problem.
Most likely, some lines work and some don't.  Take just the first three lines.  Which import, which don't?  Is there any change from adding/removing lines?  What do the lines that don't import have in common?
Most importantly - view the data in a regular text editor, not just a spreadsheet app.  The spreadsheet app may be hiding some irregularity that's obvious when viewing the data in a text editor.