Watercooling hoses need not be stiff.. you're just using the wrong hosing if it is... Tygon make the best hosing around, its expensive at $25 per meter, but its what hospitals use for all their hosing needs.. so thats the stiffness solve... from there, norma hose clamps are $1 each at mitre 10... Theres that solved..
Watercooling of anything need not be considered dangerous, its as safe as houses provided you think before you execute the design.
I myself have watercooled many MANY computers in my time, with hoses going between the cpu/graphics card, ram and hard drives.. all up a $6000 computer with 1.2L of water inside it... never once had a single issue...
Alex.