All I do with some 99% of all my Colocasia is sit them in the pond and let the fish and water do the food and drink for them. I have pictures of them I think I've shown on here, where they all grow quite nicely. I do think I've reached maybe saturation point with the numbers of plants to fish (food) hence I will not put so many in next year.
For me I have found that Colocasia will generally flower in year 3. But some such as pink stem will reward you by flowering in the second year if you get it through the winter. the only ones I have yet seen flower are pink stem, dark stem (burgundy), fontanessii and illustris.
On flowering, as has been said, the plant does not die and in fact you can actually tell when your plant is going to flower. Normally Colocasia produce successive leaves from the last petiole to emerge previously. When they are readying to flower, you can see a distinct move to having two separate growing points. This is because the main one will still produce leaves as before and the secondary one will produce flowers. These don't emerge from successively new growth like the leaves though, but more as a procession from the one petiole that it sends up for them to emerge from.
Fontanessii yellow flowers do look fantastic alongside the dark plant and smell of papaya