5th Round is 26th/27th April isn't it

ESO,

I make it 7 all C/C1 ties with outside chances for:
Batley v C*s
Halifax v Widnes Vikings

There could be more C/C1 in the last 16 that SL teams (though I doubt it).

You're right - worst case scenario is 9 SL and 7 champs! Brilliant, and highly likely the QF's will see a couple of Championship teams.

Just out of interest what is the prize money for reaching the quarters?

Statistically, the most likely outcome is one all-Champs tie in Round 5.