Looking for some advice on a couple of questions regarding London's Heathrow (did a search but couldn't find anything that addressed my specific questions). Here are the details: I'm arriving Terminal 4 on CO 28 at 6:45 AM. My business associates are arriving Terminal 3 on AA at 9:30 AM. Our company arranged the transport so we all have to ride into town together My questions are:
1. After arriving, can I go straight to the Holideck lounge in T4 and kill time until I need to wander over to T3, or will having to pass through immigration/customs eliminate any chance of that?
2. If I can go to the Holideck lounge, what about my checked bag - will it be OK down at baggage claim for 1 1/2 hrs or will some authority probably decide its owner is MIA and take it to lost/found, or worse?
3. How do I get to T3 from 4 easily after clearing immigration/customs?
4. If the answer to #1 is NO and I have to exit the secured area after landing, any advice on killing 2-3 hrs in T3?

Thanks for any help!