Hazza,
You have a lot of questions there.
You may find the answers faster by using the search facility on this forum, or by using Google to search within this forum (Advanced Search, put site URL into the "Search in Domain" field, then add your search criteria - search for phrase, and/or/not terms can be added too)

Here is one answer for you.
5. No, just strain out the big bits of food and any rodents which have drowned in the oil. You can use flywire to achieve this. Any other contaminants should be settled out into the byproduct layer when the conversion is complete.

Have fun getting greasy,
Tony