Creating sensors

Hello, i am trying to simulate an underwater simulation in Unity, i am already using the TCP package for ROS-Unity and i have the following problems and doubts.
1º There is any loss between the msgs?
2º I have simulated a DVL and now i need to simulate a 2D sonar. I don't know if using a lot of Raycast to get the distances is a good idea. What would you do for this?
3º Can i send from Unity to ROS the images from video capture? I have a script that already saves the photos from the cameras on a folder but i don't know how to send the image to ROS and how to get the image after that. Do i create a matrxx on the mesage or there is a function for it?
4º I have seen some underwater effects for the cameras, like this video, but they usually look very cartoonish and they are mostly blue all the time which is a problem because i need to search realism. I also have a problem with fog and underwater valleys where the fog nearly dissapears so i am searching alternatives to that. Any idea, papers, assets or examples from tutorials on how to make it?
5º Any recommendations of a tool for making custom terrain? I am using terrain generator from Djetty right now and i am getting a lot of lag when i use his tool for putting trees, plants and stuff.
6º I am focusing these simulations for AUVs and ROVs but if the simulation is going to be near the surface i want to have waves. I have seen the simple waves(which most tutorials are about), the FFT and the gerstner waves. There is so much difference between them or using the simple ones is better? After all the ocean surface is not going to be a focus because most of the sim is going to be underwater.

I know there are a lot of points so thanks for your time for reading and if you answers thanks a lot for the help.