On June 2 I'll be flying from Berlin to LAX via LHR. Both flights use T5. I'll be flying World Club (long haul business) so I'll have access ot the lounge. I arrive at 8:30 and my continuation is at 4:00 so I think I have plenty of time. The idea would be debark, go to the lounge, check my bags, grab a bit of breakfast, then call a cab from Windsor, tour the castle and maybe Eaton, then grab a cab back to LHR, go back tot he lounge until the flihgt.

Here are my quesitons:
1: When I arrive at T5 will I have to collect my bags and recheck or will they route through to LAX (I'm guessing they will)
2: Will I have to go through customs/immigration if I just go to the BA Lounge (guessing not)
3: Will I have to go through Customs/Immigration if I exit the terminal (guessing I will)
4: If the answer to 3 is "Yes,' how does it work? I've flown through LHR many times, but so far avoided T5. In other pure international terminals you are "guided" from the plane to baggage, to immigration, to customs and then out. If I'm right that if I went just to the lounge I'd avoid this hassle, that means that I would have to be "vetted" somehow when I left the terminal, not when I left the plane. Trying to figure out how this works.
5: Coming back to the airport I know I'd go through security. Does BA have expedited security for World Club? Normally I don't mind the regular wait, but since I'll be packing things tight it would be nice if there was a quck way through.
6: Can I check my bags at the World Club lounge for several hours while I do this fools errand?

Any input, particularly from folks who have done this side-trip would be greatly appreciated. I just hope I'm not biting off too much to chew.

Many thanks.

HLB