There isn’t any way that I know of to get all of the sub fields at once. There isn’t a get_sub_fields() function, although it has been requested before http://support.advancedcustomfields.com/forums/topic/get_sub_fields/
You need to get or display each sub field.
As far as the difference between get_ and the_, as you said. the_sub_field echoes the value, it does not return anything. Let’s say that a sub field contains a url.
If you do this
<a href="<?php
the_sub_field('link'); ?>"><?php the_sub_field('link_text'); ?></a>
then the url and the text will be output where they belong.
If you instead tried this
<a href="<?php
get_sub_field('link'); ?>"><?php get_sub_field('link_text'); ?></a>
both the link attribute and the text of the link would be blank.
get_sub_field() is useful when you need to assign the value to a variable, usually because you need to do more with it than simply echo the value.
