For your production machine, use Debian and the Koha packages, your life will be a lot easier.
See the comment for installing.
This might seem counter intuitive but the less resources your organisation has, the more important it is to get any changes you make upstreamed in to the project. If you don’t have the resources to do this, you certainly don’t have the resources to maintain your changes through every upgrade.
Get involved in the community, this conference is the first step along this path. Koha works because it has a huge community behind it.
Work with organisations that understand Free Software. They are easy to spot, they are heavily involved in the community.
Always upgrade on a test machine first, with limited resources this is sometimes difficult. Perhaps explore sharing a development/test machine between organisations.
If you have ideas for new features, file an enhancement ‘bug’ at bugs.koha-community.org. It may not mean someone will automatically work on it, but others might think it is a great idea and want to work on it.
Understanding Free software is about Freedom, not price.