Too many questions, but I hope I can help you a bit.
Concerning your first question. There is no means of transport from Delphi to go to Kalambaka. You have to return to Athens after the tour to Delphi, take your time there and return to Athens and get the bus to Kalabaka the next day. http://www.ktel.org/index.php?pathID=1_2767_2813http://www.holidayshop.gr/textsEn.asp?ElementId=6797
The other alternative is to get the train from Livadia to go to Larissa, and from there you can easily pick a bus for Kalambaka. Larisa ĖKalambaka is approximately 2 hours.
I think it would be better to get a tour than go on your own because you might find difficulty in the bus schedule and time of departure from each destination.
No, if you pick a good tour there is no rush at all and you will surely enjoy it. Donít worry about this.
As for the islands, Naxos I believe you can have a faster access from Santorini to Naxos but you can always see and plan going to the other trip when you are there.http://www.greecelogue.com/ferries-from-sa...and-return.html
Sifnos is another interesting island for sure!
It is good that you spend one or two days in Olympia and just see the sites in Corinth and come to Athens. Take your time in Olympia there is much to see there.
Have in mind that you just need a day to Meteora and donít stay that much in Kalambaka. There is nothing special to see in Kalambaka other than take photos of the Meteora from a distance. You can save these days and spend it somewhere else.
You can spend one night at Kalambaka and take the bus for Trikala. It is a nice place to visit.
Donít pre-book tickets for ferries or for buses!
I hope there wonít be any protesting in Athens those days.
If you are in Athens take the bus from the same bus station (Lyosion) and in an hourís time you will be driven to Chalkida. http://blog.travelpod.com/travel-blog-entr...12036/tpod.htmlhttp://livingingreece.gr/2008/06/13/ktel-buses-of-greece/
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