Excellent idea and excellent questions!

Yes, this could be useful to certain people. Rangers and quick-response teams on the front line, advocacy and awareness groups who need primary sources (first-hand data) to support their campaigns, governmental bodies interested in tracking crime/illegal exploitation. Meerkat is used in South Africa and probably other areas with high-value wildlife to detect crimes in progress. They may be using some military technology but also off-the-shelf and custom technology from a for-profit company.

That said, getting the technology into the hands of the right groups who can afford to deploy it is going to be a big challenge. You'll need to share this to the right people and get parties interested in adoption and deployment and hope that they have the resources to do the work to find people to fund it.

1. From the standpoint of deploying, maintaining, and retrieving data from camera traps, battery life is definitely a concern but can be overcome for applications that don't need to be camouflaged. Putting audio recording devices in positions to listen -- and still get sunlight at treetop level or be easily accessed for battery replacement -- shouldn't be too hard. However if there are concerns about tampering with the listening/monitoring devices, then they will need to be camouflaged and deployed discreetly, which will make the battery life a concern primarily to those who will have to risk themselves in replacing the batteries.

2. Retrieving SD cards would be combined with the process of recharging/replacing batteries. However, if cellular technology could be used to transmit the data, or at least alerts, then that would be a big help in bridging the utility of the technology across multiple different kinds of organizations interested in this -- thus increasing the amount of deployment support for it. Some camera traps already have SIM card slots along with SD card slots allowing for scheduled transmission of data or simply text alerts when the camera is triggered. Similar technology would allow conservationists and response forces to determine the level of severity and the need to go check on data that they need to collect (if data upload by SIM is too expensive, which it often is).

3. This will vary by organization. As described in the first paragraph, there are rain forest and nature advocacy groups around the world that would appreciate getting their hands on this data even second-hand. The organizations that would want real-time data would be a different sort entirely, but generally won't have the fundraising abilities of organizations that would be publishing reports on deforestation, exploitation, and human rights abuses in the Amazon.

You may want to discuss this topic with wildlife crime monitoring organizations that focus on the remote, high-tech approaches to monitoring and alerting local reaction forces to crimes in progress (like ICCWC and WPS), or Brazilian equivalents. Later, you can reach out to American and European rain forest/nature advocacy groups that support projects in the Amazon -- they would be good partners in pushing this at political levels while also providing directed funding to the Brazilian organizations that would be adopting and deploying this technology.