Can I also do individual tax returns with the TURBOTAX BUSINESS TAX YEAR 2018 WIN DOWNLOAD product?

No, TurboTax Business is just for business returns--1065, 1120S, 1120, or 1041.  You would have to use the Online or CD/Dowload versions of the personal editions of TurboTax:

• CD/Download:  https://turbotax.intuit.com/personal-taxes/cd-download/
• Online:  https://turbotax.intuit.com/personal-taxes/online/
  

The TurboTax Business Edition does not support personal tax returns, Form 1040 - https://turbotax.intuit.com/small-business-taxes/