Does the system need bypass dampers?
Short answer: no.
Long answer: the system takes care of excess static pressure in a different way.
Longer answer: here.
Short answer: yes and no.
Long answer: of course, they are better from cost efficiency standpoint. However, "what you get is what you paid for", to some extent. The register based dampers are not as good as (allegedly) precision engineered airflow dampers, however, good registers may do a better job than "entry level" dampers. Another disadvantage is that the registers are almost guaranteed to create an air velocity loss because they are not placed at strategic locations, as the dampers are. This leads to lesser efficiency.
However, exactly as there are people who can afford Huyndai and can't afford BMW, there are people who can afford $10 dampers and can't afford $200 ones. The poor people suffer from heat and cold exactly the same way as the rich. If you can't afford $200, $10 will definitely make your life easier.
With single stage A/C, there is a limited ability to protect the compressor from high temperature differential at least by shutting off the compressor while letting the fan run. This is a theoretical answer, from the practical standpoint it is yet to be seen how high the temperature difference will get when the airflow is restricted in a way it is being done by this system.
The best answer to this question is: use multistage compressor coupled with variable speed fan (see Homeowner's FAQs). This way, fine grained control is possible.