Linen is traditionally worn as a summer outfit for a casual setting. In terms of formality wool is still the choice. So other than considering the suitability of a fabric for tropical climate you also have to decide for what occasions it will be worn.

^Don't really understand your question. A canvas is used regardless whether it is a full canvassed construction (floating canvas) or fused (glued). It is what gives the suit shape. You are concerned about the thickness(?), but there should be no difference in the thickness for either construction.