ifdef-highlighting VS vim-plug

All those vim.org scripts also have a github version https://github.com/vim-scripts/ifdef-highlighting which I tend to use with my plugin manager (although vim.org links also work, I use https://github.com/junegunn/vim-plug but there are others that work similarly, and vim has one built in.) If you do it like this, you don't have to think about how to install it, just add something like Plug 'vim-scripts/ifdef-highlighting' and you're done.

vim-plug

I encourage you to add plugins to your vim (tip: use vim-plug). Use vimawesome.com for inspiration.

Personally, I like https://github.com/junegunn/vim-plug

But the plugin manager https://github.com/junegunn/vim-plug can also install from offline sources, without accessing Github:

To get started, simply install the plugin using your favorite plugin manager, such as vim-plug or packer.nvim. You can find detailed installation instructions in the README.

Not sure if Vundle did anything particularly fancy, but I'm using vim-plug [0] and have no complaints. It stays out of my way to the point that I had to look at my .vimrc just now to make sure that's what I was using.

[0] https://github.com/junegunn/vim-plug

I chose to move on to vim-plug and can report it was a simple switch from Vundle.

A plugin manager like vim-plug.

Emacs is a good software for LaTeX along with its plugin AUCTeX but you don't need to switch to Emacs since you already are a Vim user. I would recommend to install VimTex (make sure it is NOT VimLatex) using any package manager, e.g. VimPlug.

recommend first setting up a proper plugin manager : https://github.com/junegunn/vim-plug