In an interview with Spaceflight Now last week, Bridenstine cited several focus areas as SpaceX and NASA march toward launch of the Demo-2 test flight. They included completing two final parachute tests, data reviews, and ensuring the astronauts and ground teams remain healthy during the global coronavirus pandemic.

One of the two remaining parachute tests was successfully completed last weekend after dropping a test rig from a C-130 cargo plane. SpaceX changed the testing plan after a helicopter drop test in March was cut short when the test rig became unstable, forcing the pilot to prematurely release the device that simulates the mass of the Crew Dragon spacecraft. … One more parachute drop test from the C-130 cargo plane is scheduled for early May. That will be the final planned parachute test before the Demo-2 launch.

https://www.nasa.gov/specials/dm2/
Although the Crew Dragon being used for this flight test can stay in orbit about 110 days, the specific mission duration will be determined once on station based on the readiness of the next commercial crew launch. The operational Crew Dragon spacecraft will be capable of staying in orbit for at least 210 days as a NASA requirement.

I understand that they want this one back about one month prior to the launch of SpX/PCM-1 (Post Certification Mission 1) so they can study the capsule and its reentry, landing, and recovery performance before committing to the following launch.