Hi there,
Canna indica is actually a hardy garden plant, so doesn't need to be grown indoors unless you particularly want it there. If you are growing indoors then you will need a position in full light for it to prosper and flower.

In answer to your Qs. regarding watering, they are sometimes used as aquatic/marginal plants grown in 15cm or more depth of water, so they do like a lot of moisture & it would be impossible to over-water through the growing season.