For the most part, the older tutorials on Youtube and on the forums are almost all still applicable in most cases for the 1.15 patch as not much changed within the 1.15 patch that changes how you export and download items and such. But, a lot of the content here on the forums was accidentally erased so I can see how finding the right information might be troublesome. I want to do my best to lead you in the right direction.
1) Positioning Portals & Linking Maps
The link that Chipz provided is a good tutorial for finding information on portals in the map maker. I hope it helps c:
2) Mesh, Material, Particle, & Item Downloads/Exporting (I Tried The Default Exporting Tricks That Worked 5+ Years Ago But It Clones My
Are you asking how to download and how to export meshes, materials and items? If so, I hope we can find you the information you are looking for. It is somewhat different on how to do these for each of what you seemed to ask. I will do my best!
3) Files & Messes Up My Game So I Need To See What I Could Possibly Be Doing Wrong)
I'm not sure what you're asking here. Would you mind clarifying for us what the problem here is? c:
4) Changing The Default Skin/Mesh/Texture On Items (Like Fluorite Crystals For Example From The Blue They Are Now To A Starry Night Sky)
Changing the textures on objects within the game is as simple as replacing the current object's texture within the folder that the object is held. For example, you stated as an example the crystal. You can find the crystal object's material and texture files in C:\FeralHeart\media\objects\misc. What you will need to do for the crystal is replace the crystalTex.jpeg file with the texture you would like it to be, with the same file type and name so it rewrites over it. Almost all of your textures can be changed this way. It's just a matter of browsing in the FeralHeart subfolders and trying to find where those textures are at for each object or item and replacing them with the same name and filetype with your desired texture. It is also possible to edit the material files to contain different texture names but that requires a bit more knowledge on the subject. If you are familiar with preset materials, editing materials might be a bit easier for you. However, I recommend simply just replacing the texture files.