ESTA visa waiver

The application form first asks if you "have a current or previous employer." If this is not the case, just answer "no" and leave the address blank. If you do have a previous employer, you could answer "yes" and fill in as much information as you can, looking up the address online, or just indicating where the information is unavailable.

Your second question is addressed by the ESTA help center:

CAN I APPLY FOR AN ESTA WITHOUT HAVING CONFIRMED TRAVEL PLANS?

Yes. Specific travel plans are not mandatory at the time of application, but you will need a U.S. point of contact.

Although specific travel plans are not required, the address where you will be staying in the United States is recommended to complete the application. If multiple locations are planned, you only need to enter the first address. If a complete address is not known, you can enter the name of the hotel or location you will visit.

If you are in transit, please select 'yes' to the 'Is your travel to the U.S. occurring in transit to another country?' question in the Travel Information section.

You don't need to have a full itinerary for your trip or even confirmed reservations; just pick somewhere. You may, but are not required to, change the address later by going into "Check ESTA Status" after your application is approved. You may also change your plans once you are in the US as you see fit, provided that you leave the country on time.

You can contact US Customs and Border Protection with your questions, though the usefulness of their answers is known to vary significantly.