How to setup a line length marker in vim/gvim

Windows gvim uses Windows' cmd.exe to execute :! commands and cmd.exe does not understand ~ as an alias for $HOME. Also, cmd.exe accepts only \ as a path separator, not /. Try instead

:cd ~
:!mkdir Documents\new_folder

Since :cd is a Vim internal command, Vim will correctly expand ~ itself.

[Edit: Added ! in front of mkdir (typo), changed path separator from / to \ (mistake) and added sentence about it.]

Indentation in vim can be a little hairy.

You can configure vim to either insert a tab character or insert some number of spaces when you press the tab key using the expandtab option. You can also configure how wide tabs (how many spaces they take up) are with the tabstop option. Finally you can also configure vim to display tabs with a special character using the listchars option (▸ is a common choice). However that character won't be shown where spaces are used in place of tabs. That is why some of your tabs have a special character and some do not, some of them are actual tab characters, and others are just a lot of spaces acting like a tab.

It sounds like the remote unix server was configured with expandtab on and tabstop set to 6, so when you enter a tab, it outputs 6 spaces, while you're development server seems to be configured with noexpandtab and tabstop set to 4.

To fix this you can use vim's find/replace functionality to replace all occurrences of six spaces with a single tab using the command :%s/ \{6}/\t/g. To understand that command you should read up on vim's search and replace capabilities here. To keep this from happening in the future you should make your own .vimrc file that sets things up the way you like it and either place it in your home directory so it is automatically loaded or :source it whenever you edit any files.

Note: There are also other tab options such as shiftwidth and softtabstop but they aren't as relevant to your problem. However you should read about them so you can configure vim to act exactly how you want.