Well. I understand that it's really confusing because we use two different words which are equivalent to one in English. Я иду на пляж - it means that I am going to the beach by foot But if Я еду на пляж- I am going to the beach by bus, car or train. Please, pay attention that I use present continious here. Я хожу на пляж- means that I usually go to the beach every day or every week. In short I do it regulary. Я часто езжу на пляж на машинею mtans that I go to the beach quite often by car. I hope it helps. If you have any additional questions, please don't hesitate.

Truth be told Nobody knows :)

There are not any difference absolutely. You can use any variants. it will be correct in any case.

Could you, please, give an example? What makes you confused? идти или ходить?