Currently the product is completely free. Eventually a charge of 1-2 USD per region per month may be levied (payable in L$, currently 250-500 L$/regionmonth). This charge is to cover the cost of the compute resources consumed running the product which covers bandwidth, storage and compute charges for the 2 Amazon AWS instances that run the cluster. This should not be seen as a payment for my time or the product, simply the resources necessary to provide the service product which remains freely supplied. (I'm not in this for the money, and if I were I doubt Second Life provides the most meaningful return on time invested).
Yup, this website, https://sl.coagulate.net/Docs/GPHUD/, contains documentation about components, example uses and a collection of “How To”s
This process varies over time, once there's a charging infrastructure in place this will likely be all “self service”, however, for now:
Feel free to contact Iain Maltz if you need any guidance with the user of the product ; it can be both simple and very complex and providing support in getting the most of the product is expected.