I found a really good site: Raildude.com. It's free and they are pretty knowledgeable about the best train deals. almost 8 years ago
Flying LAX to London with 2.5 hr layover before flight to Dublin, is that enough time to go thru customs and get to different terminal?
Yes. I recently had a layover at heathrow and there was a direct lane for passengers connecting to other flights. It was a pretty smooth transition. almost 8 years ago