Linux, Open Source and the Organisation

How does open-source software support these needs?

There is almost certainly an active community of people using the same software, who will share the costs of maintaining and enhancing it.
If no-one else is maintaining the software you need, you can maintain it yourself
- Or pay someone else to
If you need an enhancement, you can write it yourself
- Or pay someone else to
Your data is safe
- But you may have to put some effort in.