Asmodeusnim

Okay, I think my friend and I solved this because one way or another we got it to work...though I'm not totally sure what the EXACT issue was, I'm not gonna look this gift house in the mouth. 
What I did to troubleshoot this:
Confirmed that the VS version of the server and my local VS  were the exact same. Made sure that all mods used on the server and on my local VS are the exact same mods and the exact same version.  For some reason, just having a mod installed but "inactive" in the mod-list is still causing issues (ranging from super long load-in times to just crashing the entire client). Inasmuch as I am aware, this should not be happening...but it's also easy enough to swap out mods in VS that I don't mind having to do that if I want to play a previously existing world with different mods (and didn't look into this further). Double checked that the .vcdbs world file was put into the correct save folder. (if you don't know how to find your local save files, just go into the client as if you're going to launch an existing world and instead click on the "Open Saves Folder" button on the bottom left of the Your Worlds list).  BEFORE launching the server-world, renamed the World Name through the VS client (pencil/edit button at the right of the world in the Your Worlds list). The server host never named the server world so the file was Default.vcdbs and the World Name box was empty. For whatever reason, the world would not fully load if this box was popping up as empty in the client. I later re-named the .vcdbs file directly without any issues as well (I just like having the world name match the file name). Launch the server-world in Repair Mode. (You can do this from the same screen where you can change the World Name, its the bottom-most button on the right). While loading the server-world in Repair Mode, VS did see some issues with the file/world and I guess it fixed them? It took about 20 minutes to load the file, so I was stepping away from my PC while it went through everything (would come back to check if it crashed again or not). Once loaded into the world, take a look around and check if mods loaded correctly and stuff is as you remember it to be. Close the world and re-launch like normal just to check if you can. Hopefully it does because now it works fine! One last thing to note is that I did end up re-downloading a new copy of the server-world files that our server-host made available to us. I don't know if there was an issue when I downloaded and extracted the files the first time around, but the first copy of files would not run in repair mode! It would crash the entire client if I tried and the VS client wouldn't have any error code report or recognize that it crashed.