I would be very interested to see videos of people's "interpretation" of hanging leg raises as I fear there's to much talk of them being easy for people to be doing them right.
Sigma, try laying leg raises and work up to hanging. Accompanied with planks I am pretty sure that will suffice for now.
A more advanced core exercise is ab wheel roll outs, if you can afford £10 then get the 66fit one from amazon. You shouldn't need anything else as you can make all 3 core exercises harder with resistance bands/chains/weights, and more advanced versions of each.
As for the deadlifts I think ice has covered everything
Just out of interest Do you take the vids on your phone??