1) There is a transit hotel, but it isn't free. If you are referring to the Dubai Connect service, there is of late some confusion about which services and fare classes qualify. I think an ex-BKK departure is unlikely to qualify as EK will point to the shorter connection time services (if they are available at the time of your booking) and as discussed in another thread, BKK is a busy station with lots of connections to Dubai spaced throughout the day. However, looking at availability on that date, you might be in luck: contact your local Emirates office and check with them to confirm.

http://www.emirates.com/uk/english/p...onditions.aspx

Depending on how comfortable you need to be to sleep, you might be able to get a few hours of sleep in the lounges at DXB if you have earplugs and eyeshades. Others have posted their experiences about the hotel in the forum - iirc, you get an escort from the plane, through security and up to the hotel which is situated near/above the lounges. As you are a QF Platinum, you will have access to the F lounges which are easier to sleep in than the J lounges. The Concourse A F lounge has quiet rooms where you can collapse. I'd still bring the earplugs and eyeshades though.

2) If you don't want to see Dubai itself, your shortest connection time is probably superior. The 8hr55 min connection is really going to turn into about 7h 30min hours after allowing for delays, taxiing and security and arriving at your connecting flight 30-40 minutes before departure. You can probably fill that time with sleep, shower, massage in the spa and breakfast. If you do want to see Dubai your 15h stopover is plenty of time to do that assuming you can enter the UAE without a visa - you'll be able to leave the airport, have dinner somewhere, see things, etc. then either check-in to a hotel in Dubai or return to the airport to nap in the lounge/transit hotel.