Hello riwi,
your first issue has nothing to do with the editor but with the configuration of putty or the terminal respectively.
To your second question: the standard-editor on Slackware is not vim but elvis. elvis is executed (by default) if you use the vi command. elvis can display html and I think this is what you mean. There should be a file ~/.elvisrc in your homedirectory, in this file insert a line with the command you described
I hope this works for you.
Markus