Caveats, pros & cons of going on CNG for automobiles

I'm driving a lot picking up passengers (up to 800km/month) & I seem to read somewhere
that CNG (Compressed Natural Gas)'s cost per km is less than half of petrol (ie gasoline as
they call it in the US).

What are the pros & cons of going to CNG?  I plan to make my car go 'hybrid' ie can take
both CNG & petrol

Q1:
I heard from a Toyota hiAce Hi-roof owner that the Natural gas 'injector' tends to break
down almost every year & it costs him about US$700 to replace each of it?  Anyone heard
of this or any parts that relates to CNG that tends to break down?

Q2:
Quite a large cylinder tank will be installed in the car's boot in my country if we go into
CNG : my spouse is concerned it may explode?  Any truth in this?  

Q3:
When there's a collision or car overturned, is the chances of an explosion equal for both
a petrol (gasoline) only car or a car with both CNG+petrol?

Q4:
Is the weight of a fully-filled up CNG tank more than 30kg ?  This will increase the weight
of the car

Q5:
Is there any way/technology to compress it further so that we only need to install a
small CNG tank (& hopefully one made of very light-weight material, say solid plastic
instead of steel)?

Q6:
While running on CNG, is the car's acceleration (some call it 'pick-up' ie to reach a
certain speed within how many minutes) compromised considerably compared to
when it's on an Octane 95 petrol?

Q7:
Any other pros & cons ?
collision