If you mean that people could still apply, it would be more natural to say, “The HR manager notified all the candidates that the application process was still open.” If you mean that HR is still reviewing applications, you can say, “The HR manager notified all the candidates that the application review was still in progress.”

Great example. It would be a little more natural to say, “Before starting our trip, we should take into consideration the construction in progress on the main road, so we can take a detour.” Or, “…so we can take another route.”

Good deal! You can add to the point by saying, “Climate change is already in progress.” That adds a little urgency to the sentence. We would typically also say “heat advisory” for this sort of weather, when the weather agency warns you about the danger of the heat.

I start with active learning today. In my country the Netherlands, climate change is in progress. The next days it is so warm that there is a heat alarm.

Great!