What to consider when planning our project for endangered, rarely seen species

Hi all,

We currently have 12 camera traps deployed in key areas within a National Park to monitor our target species (an endangered thrush), the locations are meant to be hopspots for the species, but they are not standardised spacing, and could be considered as just opportunistic locations. 

We want to improve our sampling methods so that the data can be analysed robustly.

What do we need to consider?

Obviously we'd like to purchase more camera traps, but even with the few we have perhaps we can position them in a more strcutred way to answer a specific research question?

Research Questions of interest to us are

1) population density of the Thrush (we already know distribution more or less)

2) distribution (extant of edge effect for the national park) and density of predators (monkeys/civets/rats) 

3) seasonal changes in 1&2

I'd be grateful for advice on a) which questions can we ask ,b) suitable trap placement design) and c) which stats could be used to answer.. 

Many thanks!