Day trips from Dubai

I will visit Dubai on November of this year (2018) with my mom and I planning to visit the place by my own however I have some doubts that maybe an expert in this fórum can help me:

(i) I read that there is a railway service, have they start to render services for passengers from Dubai to Abu Dahbi, in its case upon when.

(ii) What is the best way to get to Abu Dabi? Bus or rent a car?

(iii) Driving in Emirates is complicate due to traffic jam or complicate like Cairo?

(iv) I am hesitating either to visit Sharjab or Fujairah? What do you recomend? What is the best way to get to this places?

(v) Fujairah it is my understanding that is a bit far therefore maybe is better to get a tour, in which case which one do you recommend? My mother does not speak English therefore the tour must be in Spanish? Is it worthy to visit despite the distance?

(vi) Is it posible to get to Muscat in a day tour? It is my understanding that is complicate to get a visa (I am Mexican)?

Any guidance will be highly appreciated to plan my journey.