Differences between Mission Planner for APM 3.1.0 and Pixha

I have been using Mission Planner for the APM 3.1 board, now and considering to update to Pixhawk board , will I need a different type of Mission Planner ???
-Will I need to relearn a whole lot of different commands ???
-Is the way that we program WayPoints changed ???
-Will I be able to use the old Mission Planner params files for my photogrammetric projects ???.
-Is that mean that there will be no further hardware-software development for the APM 2.6 ??? I mean can we expect a future APM board i.e 2.7 or 2.9 ???
Kind regards to anyone who can clarify above questions.

The mission planner remains the same, you will be able to do more with a Pixhawk. I don’t think an APM 2.7 is on the cards, I could be wrong there.

Simple answer same GCS more features.

Hiya Gary :
Many thanks for your very helpful and prompt reply.
With this information in mind I can go now and find how to make the transition to a new quad using PIXHAWK with my “ old methods “ I mean …I assume that the calibration procedures for the new gps and compass module are the same , and the “setup… compassmot …motortest ,ect “ have not changed… I guess it would be very helful if there was a single centralized “page/site “ which was dedicated exclusively to APM 2.5 board users –old GPS and all – that wanted to replace “ in the same quad “ the changes ,if any ,needed for making the transition to the new awesome Pixhawk board/system.
I do not know about anybody else , but having a very clear process of how to make that change , will certainly speed up the time it will take me find out – exactly – everything I need to do or buy before investing in the Pixhawk . This is a standard process for me ,in any upgrades I make to any hardware or software I am intending to work/invest on…and I am not talking just about money …time researching for information can be the biggest investment of all…well in my case anyway…!!!.
For all I know there might be a centralized page /site with all this information already….in which case I will be very happy indeed not to mention amount of hours saved…!!!
Again Gary , many thanks for your help , and your time.
Cheers…!!!and happy flying…!!!