Oil And Gas Formation

Generally the scientist believe the crude oil and natural gas are formed by live things. Tiny sea plants and animals died were buried on ocean floor. Over time, they were covered by layers of sediment and rock.
Over millions of  years,the remains were buried deeper and deeper.The enormous heat and pressure turn them into oil and gas. They migrated from the source to the reservoir rock, and trapping by impermeable rock.

Question 1:  Is this live things transformation process continuous? Today a fish died in sea, would it become oil over millions of year later?

Question 2: Why from live things? Live things contains protein (CO-NH), Is amount of hydrocarbon to O and N ratio in reservoir reflect protein ratio?

Question 3: Formation oil and gas need the right temperature and pressure. However found some oil in surface only few meter from ground which is no high temperature and pressure condition.

Question 4: The hydrocarbon was found in some of planet, like Saturn, Jupiter, but without biology.