Modify Excel File Data - 680 Data Fields

Need 680 data fields updated in Excel file. I need the following corrections to be made in the Column C (ie Keywords) data fields of this Excel file. The keyword data needs to follow these 4 rules as listed below.   1. All compound words or phrases should be hyphenated (real-time people-in-the-background ferry-terminal etc.) 2. Make all nouns plural (except for proper names) 3. All keywords in lower case (except for proper names) 4. No commas between keywords, only blank spaces   The first three rows of Column C (Keyword Column) have been completed as examples - see attached Excel file. I need the other 680 Keyword data fields in Column C (see attached Excel file) to be corrected according to the 4 rules as explained above. The ONLY corrections needed in this Excel file are in Column C, the rest of the data in the other Columns are to remain unchanged.