Arriving to FRA on LA 705 that is on average a half hour delayed and has a 10% extremely delayed status.

Will oneway fares on DB ICE always be the same as the oneway fare that comes up on the net. Are there ever any discounts buying just before departure? I assume not.

I find DB has fares now called Surf and Rail that appear to only be sold roundtrip in advance on net. On the FRA CGN route the ow is 55 euro but I find these fares for 39 euro rt.

Is it therefore advisable to book these?

If I am unlucky and severely delayed to FRA how does DB deal with situations like this. If I book much later train will they be able to change to earlier at FRA?