What should an administrator use as an identifier when importing and updating records from a separate system?

Sales reps at Ursa Major Solar are having difficulty managing deals. The leadership team has asked administrator to help sales reps prioritize and close more deals.
the administrator configure to help with these issues?

The VP of sales at Universal Containers wants to prevent members of the sales team from changing an opportunity to a date in the past.
What should an administrator configure to meet this requirement?

AW Computing has six sales teams in a region. These teams always consists of the same account manager, engineer, and assistant.
What should the administrator configure to make it easier for teams to collaborate with the same customer?

DreamHouse Realty (DHR) wants a templated process with a mortgage calculator that generated leads for loans. DHR needs to complete the project within 30 days and has maxed out its budget for the year.
Which AppExchange item should help the administrator to meet the request?