Hi Nadia,
You won't find many PhD applicants on this forum. In any case, getting a visa approval is very easy if you have an offer to do a PhD - because these are almost always funded by the university itself and the visa officer will have no doubt that you are a genuine student (or you wouldn't be doing a PhD in the first place).
If you want to learn more about individual PhD programs and their admission requirements, you should read websites of the universities you are thinking of applying to. These are generally very informative and helpful. If you want even more information you can always send an email to the relevant university department.
Best of Luck
