UK

The criteria is mostly excellent scores and grades.

Yes, if you can get admission in oxford or brookes it is really worth to pursue it. It is good for your personal growth and exposure as well as for career opportunities. You will easily get brilliant packages in any company you wish.

It is your choice. There's no point in getting a visa that early. You have to factor in other things like value of pound, political stability and other rule changes etc. Consult with an education consultant and ask for their opinion. P. S - if you haven't completed IELTS complete that first. Even if you pay the amount, you are gonna get a conditional offer letter and not an unconditional offer letter. So it's better to complete your IELTS before paying. But do check whether there's a deadline for fee payment. Enquire directly with the University if you don't trust the agent.

75% is the requirement as far as I am aware.

Among these three, Australia is the cheapest. And the fee structure depends upon the course.

The score depends on the programme. What scores are you looking at?

There are plenty of Masters in management programs on offer in UK. Most of them would be for a period of 1 year. Almost all the universities in UK have that programme on offer.

Yes, you can apply as you are not having any Indian degree, so this will be easy for you to do it well.