To clarify a couple of points:
1. Slots are issued 2 hours prior to the EOBT. However you can see a forecast of what your slot MAY be once the FPL is in. This means that if you can see a possible one hour delay you can route around the airspace if you think that will be benifical. Sometimes however if the delay is due restrictions at the destination or departure airfield you have no choice but to live with it.
2. The RFI message is the default setting of any flightplan with an issued slot. Basically if a better slot becomes availalable for you it will automatcially be given to you without having to file an RFI.
3. The system has to be told by use of the SWM message that you want to be asked before being offered a better slot.
4. Once the aircraft doors are shut then the crew can request a REA (READY) message be filed. This can only be done by by ATC. Aircraft operators can not ask this themselves. Basically it tells the system you are fully ready to go as soon as they can find a better slot for you.
5. Yes Ops must delay your ongoing flightplan but as always this requires good clear information. Not always easy especially for us smaller boys without ACARS or flight tracing. For example if you have a slot delay for the first departure of the day, and we delay all your subsequent flightplans, then your first slot gets cancelled and off you go on your merry way....well you can imagine. We have to cancel all the delayed plans and refile, now they count as late filed, which means end of the queue when any other slots are dished out. Also if your ETA has you inbound at say 1020 and you have an outbound slot of 1055 what do we do. If we delay to give you more time you lose your place in the queue and could end up with a 1300 slot! Imagine you hold for 10 mins. By the time we realise your now on the ground and trying to turn round you have only thrity minutes. Its juggling guys and yes sometimes balls get dropped. If its tight then talk to each other to see what can be done.
Still much prefer this to the days of calling indivdual FMU's. And still believe generally delays are less in total these days.