You can definitely do both in Twine. Google "twine minimap" and you'll find a script for a minimap that moves to display different locations as you set x and y coordinates. It requires a script page and a stylesheet, but if you read the thread you'll get all the usage explanations and fixes that you'll need.
I'm sure there are inventory systems for Twine also as I've seen mention of using them, but I haven't used them myself. My needs have been more limited so I've opted to just hijack the StoryMenu page with various conditions upon which to display links and other stats.