Questions for a specific Thermal Camera

[NiemalsSebi]

Hello guys!
I want to do a project where I need to measure the skin temperature of pigs from ~3m distance.

So of course I have alread done lots of research for specific cameras and have come across multiple companies (Flir, Hikvision, Thermal, Abus, ...).
While many of them are fit for my purpose they're either A) too pricey or B) lack information.
Of course I have also looked at a coupple of studies and appliances in the medical field (e.g. Fever detection, COVID, .. However they are well fit but too expenisve)

So here are my details for my project:

• The thermal camera is mounted on a wall in a box in about 3m distance to the pigs.
• The thermal accuracy needs to be at most +-0.5°C (Which seems to be the standard without a Blackbox or too expensive camera)
• I want a resolution of at least  256x192 if possible.
• While I dont know much of about the needed FOV, there is already a normal camera mounted up there for pig counting which has a FOV of 50° and a resolution of 480x320 which is good enough.
• I would like it to be a camera [Best case a bi-spectral one], However handheld is or things like "phone cameras" are fine if they have a wallmount.
• They price of the camera should be <1000€ if possible however <2000€ if needed.
• It is important for the Camera feed to be quickly accessible either via Live Feed [Web, Network, USB, WIFI] OR the pictures can be quickly dumped via one of these things.

And here are some other questions I have about thermal imaging:

• How important is the temperatur of the sensor for an accurate reading? - How much error can be introduced by the sensor reaching 40°C instead of 30°C?
• How does the ambient temperaeture (5-30°C) affect the reading of the object? Because air has different densitiy and stuff
• Can Thermal Cameras which have e.g. +-2°C on a range of -20...200°C be calibrated to have a error of +-0.5°C for 20--50°C?? IF so, how?
• Does the error of a thermal camera say that it has a max. error of 2°C ALWAYS?? e.g. if the object temp is 50°C my camera can say 51°C today but if i try it again it could say 48°C or will the reading always be the same??
• How do blackbodies (reference sources in the fov of the camera) help calibrate the camera? 

Some of the cameras I have already looked at and think could fit my purpose if 1 things could be changed:
Hikvision DS-2TD2628-3/QA [+-8°C error??]
HIKVISION DS-2TP31B-3AUF  [Cheap, good error +-0.5°C, low resolution, no live feed]
DS-2TD2617B-3/PA [EXPENSIVE?]
HikMicro Cube [Not fit for purpose i Think?]

I am sorry if I have posted in the wrong thread or this question has been answered thousands of times already. If so please link me to the corresponding post.

If you need any further details please ask.

Thanks for reading and explaining the world of thermal imagery to me

EDIT: Format, Information