Engagement

  This is not permissible at all and it is unacceptable by any person who has modesty. As for the questions, there are so many of them about his prayer, his reaction in cases of anger, his knowledge etc.

If he is serious, the answer is yes.

Yes, it can. This depends on the circumstances and the traditions. It might be better to have a month or so between the Nikah and the actual marriage so that they get to know each other more.

Yes

It is not permissible for a stranger to talk to a girl without any legitimate reason. Such a proposal must only be addressed to the father or to her brother. Talking directly with the girl is not permissible.

Yes, he can.

  If the marriage conditions were fulfilled, the Walima is not one of them but it is Sunnah, therefore, their marriage is correct as long as there were witnesses. Whether the Walima is done in his country or in her country, this is not an issue and all is permissible.

If she is a practicing Muslim woman and there is no legitimate reason for breaking this promise, it is not recommended to break it. But if she is not a suitable woman or not practicing or is not chaste, you must break your promise.

This differs from one person to the other. Observing the prayer, good temper and fairness are among the good characteristics.

It can be done both ways.