Welcome to the addiction. I'm glad to hear you're ready to go big!
First and foremost, I'd like to remind you that there is sequencing involved in this hobby. For this time of the year, it might be best to start with building the tree and buying songs pre-sequenced. Look at wowlights.com or holidaycoro.com - both offer services. I don't recommend one over the other, or exclude any services from other vendors, but these are two I've seen as most popular.
As for software, I recommend you download LOR's S4 Sequencing Suite and learn the software so you can build your show. Additionally, I recommend buying an FM transmitter to broadcast your music. Use radio-locator.com to find open signals to use. Please let me know if there's anything else I can do to help you.