I want to make a mini panel loaded with the fields of the "Node being viewed". But I don't know how to make this happen. Any suggestions?
This requires that a node context get passed into the mini panel for it to know what node to pull the data from. Unfortunately there is no way to pass this context using blocks.
You can use page manager to create a node view page which has the correct node context and put the mini panel there.
You can create a view that has a default argument set to get the node id from the URL. Then create a pane display on this view. You can add this view to the mini panel and it will get the node info correctly so you can use blocks.
I do not think so if mini panel is the right choice for this type of requirement. Have a look on this module CCK Blocks.