Kenny has good advice about most of your other questions....

About the SI image....Can you post a screenshot of the SI in action...

If the fuzziness in the SI image is constant..it is probably a setting issue...transducer issue..software issue...
If the fuzziness in occasionally..it could be bubbles ..from turbulent water, prop wash..etc..bubbles make the SI image fuzzy or hazy..but generally clears up after the boat gets into other water that has no bubbles...

A screen shot of what you are seeing would be very beneficial...

Rickie