Yes, you can use the 2019 TurboTax CD for a 2019 tax return. Once the software has been installed from the CD you need to be contacted to the internet so that the 2019 updates can be installed.
A 2019 tax return can only be printed and mailed, it cannot be e-filed.
Yes the Desktop CD/Download program can do unlimited returns. Go up to File - New tax return.
But first be sure to save your return with a unique name so it doesn’t get confused with another return. Go to File-Save or Save As. Because if you do another return and they have the same first name or initial as you their return might save over yours.
And be in the habit of saving Frequently! When you are done save both the .tax data file and save it as a pdf file, go to File-Save to PDF. Then you won’t need the program installed to view or print your return in the future. Like if you need a copy to get a loan or something. And save backups off of your computer like to a flash drive or burn a CD.