Building a wireless ignition system (Pyrotechnics)

Hello all,

I purchased a cheap RF based wireless ignition system this past July 4. I was immediately taken with how simple it was to use, and how convenient it made my show. That said, I started to look into more "Professional" models. These were running $300-400 and I decided that, being an avid DIY-er with an intermediate degree of electronics skill, it'd be fun to try to build my own using Arduino. That said, I have some questions on feasibility that may evolve into questions of a more technical nature.

To begin, I'm looking at using an Arduino (Uno or Mega?) to activate a set of solid state relays. I'm looking at integrating 10-12 solid state relays. I would communicate with the Arduino wirelessly via Xbee modules. My "remote" would be a raspberry Pi with an led touch screen, connected to an Xbee module.

I want each solid state relay to be pushing 18VDC@5A. This would allow me to put approximately 4 igniters per SSR cue on my launcher. I'd like to be able to engage the system from distances greater than 100 meters, so I'm thinking I'd opt for higher power Xbee modules with external antennas.

I'm thinking I'll need:

For the launcher:

-Arduino (Uno or Mega? I need some input on that) -LCD screen for debugging/seeing visual state of Arduino -10-12 SSRs rated for 3-32VDC control signal and 5-60VDC@10-20A output -Xbee module (high power) capable of point to point communication -5 high amp rated 18650 batteries in series to give me 18VDC and withstand high amp drain on firing -2 18650 batteries to power the Arduino itself

For the remote:

-Raspberry Pi -Touch screen integrated via UART -USB interfaced Xbee module -High capacity "Phone Backup" style power bank at 5V to power the Raspberry Pi

Also: Tons of programming I know little about

Bounce some ideas off of me! I'd like your thoughts, things you think I've overlooked, things you see that could be done better and/or things that look like they will go catastrophically wrong under current configuration.

Thanks!