Yes, that "arrival card" is what they want.

Google map screenshot with blue dot and GPS coordinates,

hotel booking,

nor paid deposit recipe, with date and signatures, on a hotel pillow together with room key was not enough

We used google couple of years ago. Results were not always correct, but it gave us at least the basics ideas... and just then we started to ask other people on forums...

nope

priorities... I would extend.

Or be ready to extend once you are there (80%).

It took me 12 days in fast Jakarta...

Airbnb or hotel booking with free cancellation

or find a place with 1 month notice.

Vietnam is closer to Thailand

Recurring question. Use search.

Most of the people seems to recommend Indonesia. It took them 12 days. Due to Ramadan and other Indonesian+Thai public holidays.

You don't need to be in Jakarta for this. In fact, I highly recommend you fly somewhere else, such as Yogyakarta or Bali. However, if necessary, you should be ready to travel to Jakarta.