Will I still be able to call Roman to have a taxi pick me up after I finish the game with the ‘Revenge’ ending

Apparently, there is no official record of the specific time including decimals. The seconds vary, and this is most likely because people have tried and failed to find these times. It doesn't seem like anyone has bothered trying and failing to find the decimals required to get the achievement. With other words; the decimals are currently unknown.

The times you've found are mostly the same times I've found as well, and the times you've found seem to be the fastest times. As long as you've finished the mission with a good margin to these times, the achievement/trophy should appear.

Even if OP know what happened after The Holland Play, I will explain what will happen with the Broker and South Bohan safe houses.

The first one will be the only that you will loose during the game history, but you still be able to use the parking space. During Roman's Sorrow, Dimitri's people burned down the place with Molotov's.

In the case of the second one, is an optional safe house that will require you to kill Playboy X during The Holland Play. After the mission, Dwayne will call you and Niko will explain what happened with Playboy. He will say that you should keep the apartment because the "place will makes him remind the boy a lot".

The rest of the safe houses will be unlocked after certain progress in the main history.