I just did this out and back last Wednesday. I will have a TR up for it in the next few days.

You will be able to access the Admirals Club at T8, of which there are two, based on your Silver BA card. Each lounge is located either side of the underpass so check your gate information to decide which is best. I left from Gate 1 and arrived back into a 40 series gate the next day so there doesn't seem to be any consistency as to which side of the underpass the flights are.

You should be fine on the transfers. You will have to exit the terminal buildings and head for the SkyTrain to take you over to the other terminal. In both cases security was pretty quick. If you already have a boarding pass for the AA flight make sure you enter the security from the far left where there are priority lines.

If you don't have a BP go to the far left of the check-in area where the AA premium check-in desks are located.

If you are midweek in Vegas you should be able to pick up a good deal on the hotel. It is only the weekends where the price goes skyhigh.

IIRC limo transfers to Vegas hotels were in the range of 60 USD - i.e. not cheap. Shuttle Bus was 6.50 USD.

Beware they ask that you check-in 2 hours prior to your depature from LAS which means getting up at stupid O'clock in your hotel. As an F passenger this was too cautious. I was in the lounge 90 minutes before my flight was due to leave.

I used the SSCI machines at LAS which was quick and painless. You need to walk to the other end of the terminal to clear security for the D gates that AA use. Note there is a First Class security queue which you enter via the signage that says C gates. Don't go to the next point where it says D gates as that is horredously long and is for non F pax only.

You will need to catch a transit train to the D gates midfield. There is no Admirals Club at LAS - I used the very nice Continental Lounge courtesy of Priority Pass.

Any questions feel free to PM me.