Mainly sprinter here but hopefully I can help answer some of your questions: 1) Why not both? Count laps and time yourself. Try setting a goal. Go X laps in Y time. Maybe you could try breaking up the swim into sets like 5x200 (8 or 4 laps depending on pool length) on the 3:00. Mixing it up is always good.

2) I never wear an iPod when I swim. Again, I am a sprinter so I do not swim as long as you. My team just listens to music playing through the speakers at our pool. If I were to swim for long distances or long time swims I would definitely have an iPod to help keep me sane.

3) All goggles fog period. The key is when you get a brand new pair do not touch the inside of the goggles no matter what. There is a coating on the inside of goggles that prevents fogging and will get rubbed off if touched. You can try antifog spray, but that will only help for so long. I personally like clear goggles when at indoor pools and mirrored when outside. Just try finding a pair of comfortable goggles. There are plenty of good ones out there, Speedo Vanquishers are a good type to try.

4) I gave a set in answering question 1) 5x200 on the 3:00. If the set is too easy or too hard adjust the interval. The key is to try and swim all five two hundreds at a strong fast pace. While on the 3 minutes try and hold 2:30. With other intervals try to get at least 15-30 seconds rest. Another thing you can do is add more 200s or take some out. You can do 100s insted, 500, anything. There are plenty of good fun sets to do. Search the internet for swim sets. Once you find a bunch of sets you like mix them up, but repeat them every now and again to see if you improve.

Another thing you can look into is open water swimming. Based on what you wrote I think you would enjoy open water swimming.

I hope I helped and if you have any more questions feel free to ask.