Answer 1

With careful planning around 50%-80% code reuse can be realized across-platforms. This results in faster development and reduced costs while awesome c#.Cross-platform development provides more benefits during the maintenance period. If a bug is found in a common codebase it needs to be fixed only once. also Unit tests are required to be written only once for the common code, hence the saved budget can be used to write more thorough unit tests.
I believe It is possible to use existing programming talent rather than learning platform specific development language and it is achievable with c#.
Ideal for B2B apps and business process automation apps, where time to deployment and efficient utilization of resources...it also has its downside