Confusion in IUPAC Nomenclature
Why …carbaldehyde?
It's similar to $\ce{C6H11-COOH}$ cyclohexanecarboxylic acid (not cyclohexanoic acid). It's the case where the functional group's carbon is not included in the parent structure. (Such case are also nitriles/carbonitriles, $\ce{R-CN}$)
Why not …hexyl… or rather …cyclohexyl… ?
This (wrong name) would be constructed similarly to a different, non-preferred type of nomenclature, a radical name, which names e.g. ethanol as ethyl alcohol.
There are more than two aldehydic group in the compound.
They are not. Alhedyde group is ${\ce{-CHO}}$. The other one, $\ce{&gt;C=O}$ is an oxo group (ketone). The group for suffix is chosen by the pre-defined priority, ${\ce{-CHO}}$ > $\ce{&gt;C=O}$.
Why 2-bromo-6-oxo-… and not 6-bromo-2-oxo-… ?
The groups named by prefixes (after highest priority - suffix group is assigned lowest locant possible) are not numbered by their priority, but such that the assigned locant set is lowest possible. If there are more equivalent possibilities, then they are numbered in the alphabetically sorted order (which is used in the name).