Why Shakyamuni Buddha choose Indian subcontinent as a favorable place to teach Buddhist way of living?

The five major factors were when the Buddha chose to be born

1. If it is the right time to be born as a human being in order to attain Buddha hood
2. The right continent
3. The right country or the state
4. The right caste
5. The right person chosen as the mother to give birth to

In the Indian sub continent there was many exploration of seeking for spiritual salvation during the time. No other country or time was there similar activity in seeking spiritual development and salvation. Hence this was chosen as the right time and place.

Also since the when establishing the order of monks you have to renounce you cast, i.e, what ever cast you had before is left behind and you come to the common pedestal of monkhood. Since this will not be take seriously is a low caste person preachers the set aside cast and will not gain respect of all castes the Buddha has to be born at the highest caste.

In the current situation is not ideal for a Buddha to have been born in case the Buddha to be chose this time as human life expectancy is less than 100 years. A Buddha does not appear in such times. Also back 2500 or so years ago there was no interest in meditation and meditative forms of spiritual development other than in India.

The next Buddha will be Maitreya Buddha. Depending on the time he may set Vinaya and perhaps Vinaya rules different from the current. The Vinaya is established by the Buddha and new rules do not fall into the sphere of a disciple to enact though you can have conventions or agreements, but they are not Vinaya rules. Then a new Buddha enacts his rules then they become effective. In such times the teaching of the previous Buddha would be lost to the world. The Dhamma taught by all Buddhas is the same.

(I think you know about who a Bodhisattva is....)

While a Bodhisattva is in the heavenly realm (Thauthisa) he chooses the Best time,Best parents,Best cast,Best kingdom,Best country to be born. This is an essential process that all Bodhisattva's go through before being born as a human being.

Here are the reasons why.....

As you know democracy is really new,what existed before is a cast system with nobles and lower casts. Your name sounds Indian so i presume there is no need of explaining the difficulties that a lower cast person will have to go through to get to any higher level in anything. At the age of kings there is no better place to get accepted than being born as a prince and that's why it happened like that in this era.

I have learned that there is an auspicious place on the Human realm that all Bodhisattvas (Who are destined to be A Lord Buddha) reach nirvana and become Lord Buddhas. And this place is the same place every time even after all the destruction that can happen. This time it was India and next time maybe there will be no India, Next time it may be on an island. What we are talking about is a universal position that does not change,its geography,name and other things may change but it will always be the same place in the universe.

Another Buddha can't be born in a particular realm while there is already a previous Buddha's teaching.

(Please not that this is "Theravada Buddhism" and "Mahayana Buddhists" believe in multiple Buddhas in different realms. But even them do not believe that another Buddha can be born in a particular realm while there is already a previous Buddha's teaching.)

Can Lord Buddha be a woman....

No, As Lord Buddha explained a woman who start the life of a Bodhisattva will soon turn into a male in the most nearby life and continue to be male. Because of this reason a Lord Buddha will always be a male.

Please note that this does not mean that a woman can't be a Lord Buddha. What this means is that when she start her practice as a Bodhisattva she will soon get a life as a male and therefore a woman being a lord Buddha does not happen because of this gender change between births.

Can Jesus or any other recent teachers be a Buddha....

No, Because as far as my knowledge goes none of the schools accept that two Lord Buddhas will exist in the same planet at the same time or two teachings would exist at the same time.

Will Buddhism change or modify to suit the time....

No, Because there is one unique thing about Buddhism. And that is....

Akalika = Timeless

As Lord Buddha said there is no need of updating or changing the teaching as it is timeless and complete.

Also Lord Buddha challenged saying that no one can add or remove a single teaching as too much or non worthy.

So there can be differences in

The Language The explaining method The idioms The examples

when two Lord Buddhas teach the path. But the core will always be the same. The only difference will be Grammatical and explanatory differences.