You sound like you believe you're on the right path with the second relay you ordered. I hope so, because I thought I'd worked through my own confusion on this and now I'm confused again. Tell you what... If you get the second relay, get it hooked up and it works, be sure to post here and explain how. If you can't get it working, send me a private message with phone number and email. I'll try to get in touch and help.
As long as you have the Battery and Load connections (cables to the big terminals with hex nuts) on the correct big posts, I don't think you can burn the new relay out by wiring it wrong. I think it will 1. Work, 2. Do Nothing, or 3. Blow 5A Fuse.