Well......................long question requires a long answer!
Firstly, although Qasim will give his views separately....................but his words the night before the race was that hit the Mullah river at 100kmph, and it takes you almost halfway across before you are dead slow and the rest just bully thru in first gear!
Qasim's theory on water crossing has changed from before and now it is somewhat similar to my thinking from before, i.e we do cross the small but fairly deep canal twice about 10-15 minutes before Mullah, so what ever damage can be done by hot cold hot cold is probably already done (the canal where you used low gear last time, when I crossed it this time, water came on top of my bonnet).
2ndly, we had a long delebration well before Mulla river on how to cross, and Zohaib n I agreed finally decided to go steady in high first. The thing to note is that I was probably on the widest tyres of all the racers, 275s on 8 inch rim with HT type pattern. Now that is a lot of width to make way thru water. Anyway, we entered the water in first gear at speed around 25kmph, but we had harly made thru 1/4 width when we were dead slow and the engine was dying, so we stopped n shifted to low 1st and than upto low 2nd. Total crossing time with all for me by go pro was 34sec.
And from experience, I know that if I hit water hard, somehow NPP air-intake cannot get air in and it just kills the rpm, happened on both of previous Jhal's. Bottom line the water splash wasn't intentional for me, but probably wide tyres make it look huge! 
