Actually, by memorizing the dictionary form, you should be able to derive all other forms of the verb. That is what language learning is all about. Japanese has only two irregular verbs so you're in luck here.

I don't know that for sure,but our japanese course will commence from the next semester,than i'll be able to help ya...we're ruled to pass International Japanese Exam 2,that seems to equal Toefl or Ielts for English.....then wait for some months then i can help ya...lolz^^

If you speak "miru" to Japanese native, it sounds like "look!". If you speak "mite", it sounds "would you look at this?"

If you only use て形（てform)、you can only express the present form and the progressive form. That would be enough for you to travel in Japan I guess. If you want to talk with your japanese firends or business partners, I recomend you should use all the forms. Where is your goal? It's your choice.