Can I edit the blog's theme/template, add themes or add plugins?

Blog.nus is a hosted service like Wordpress.com and Blogger.com, so your options are limited by what the Blog.nus provides.

If you need full control over your Wordpress blog, you should consider self-hosting your own installation of Wordpress.

These are the options for:

Requests to add blog themes & plugins

Blog.nus does not allow addition of blog themes and plugins.

If you know how to edit Cascading Style Sheets (CSS), you can change the look and feel of your chosen theme.

You can do this in the Dashboard under Appearance > Custom CSS.