Finding the right persons to do it is quite hard. It is also related to motivation of these persons. If they are really good, but not happy within a certain environment, you will notice it in performance and quality.
Without too many details I cannot say anything related to planning. If you want to customize AX for property management, this might take 6 month to 2 years development.
Have you searched on the internet for standard verticals on property management for AX? There are some available.