Hey Shira!
As you probably figured out from Aya you`ll find getting to Utila pretty easy.
Ive been living in Utila for 5 and a half years on and off, currently teaching at Utila dive centre Once in Ceiba you can either fly to Utila - around 25$ , and the busses from san pedro sula will stop at the airport if you ask them to, or catch the ferry ( 300 LMPS- 15 $)
which leaves La Ceiba twice a day- 9:30 am and 4pm

once at Utila everything`s a walking distance and as safe and comfortable as it gets.

by the way, you are right about whale sharks, they have been spotted next to the island three days ago.

if you need more info contact me at my email,

hotel representatives will take you to their hotel and bring you back. they wait for you at the bus station. although you can also take a taci to any hotel you want...

you have nothing to worry about.
I did exactly the same thing alone a month ago.
take the TICA bus from guatemala to la ceiba in honduras (I took it from antigua) and you will probably meet lots of tourists on the bus.
The bus arrives at mangua nicaragua at 5 pm and there are people who will take you to a hotel for the night and will bring you back to the bus station in the morning to continue to la ceiba, honduras. in la ceiba you can sleep the night (not dangerous at all. a nice place is banana republic, but any hotel will do) . in the morning you take a taxi to the ferry and take a boat ride to utila. it´s very comfortable.

btw, diving courses in Eilat are cheaper than in Honduras, althuogh everybody thinks it is cheaper there.
it costs around 220$ for open water and 220$ for advanced

hope this helped.
enjoy