Hi guys,
Some major releases would involve an upgrade fee; We expect 2 to 3 over the year, for example tvOS support, console support, new features and nodes, etc.
The plugin will be updated to the official UE4 releases.
Yes you can use the runtime-indie to place the hands on the weapon.
We have a node that does this; Documentation is available here.
For the weapon holding, this tutorial might be of interest.