First off congrats on your own hammock! The Explorer is a fine model. In regards to the original rain fly over the hex, I don't believe it to be a mistake but you may want something larger (and lighter) in the future (many people love the Kelty 12' and I've heard its reasonably priced).
As for lightening your hammock, your suspension would be a real good place to start. Whoopie slings are constrictor style rope from amsteel which is used as a nautical line. I find them much easier and greatly prefer them to the original suspension.
For insulation an underquilt is the best way to go in my opinion. Many choices are available from vendors here from down to synthetics, full to 2/3 and many widths and fabrics. You can DIY a simple IX (from DIYGearsupply.com) or simply use existing pads if you tented (just check on pad extender).
Hope this helps!
The key to immortality is first living a life worth remembering. - St. Augustine
Some people feel the rain. Others just get wet.
- Bob Marley