The 'revised' version of Genesis is how you can spin the story so that you can accommodate modern science. I'm not saying this is what Genesis writers orignally meant but if don't mind 'spin', then your questions can be answered. I only provided the spin as a way of showing that Genesis can be made compatible with science without too much effort (or too much creative spin in light of staying consistent with the Hebrew scriptures):
"It is known that life can evolve with other energy sources than sunlight, like around deep ocean vents. But the Genesis story talks of trees and seeds which certainly require sunlight."
As you know, Hebrew is wide open to interpretation since it was more suited for a poet's language than a scientist's language. Day 4 (the visibility of the sun, moon, and stars) could be translated as merely the first sunny day, or the actual creation of the universe (i.e., following the earth's formation). Hebrew is also generous with parenthetical thoughts. So it is not uncommon for Hebrew writers to throw in parenthetical thoughts just to explain the context of God's Day 4 command. For example, Genesis 2 talks about the creation of all creatures, but Genesis 3:1 is a parenthetical about how the serpent was created. Such language is needed in 3:1 in order to make sense of the story about how the serpent was able to fool Eve into eating the forbidden fruit.
So, to answer your point here, there were a few possible reasons why a young earth might have had 'low light' conditions. 1) the solar wind blew away the remnants of the nebula cloud after the earth's formation, 2) the young sun was possibly not as bright as today's sun (called the faint young sun hypothesis), 3) greenhouse gases and a strong haze are thought to have existed in the early earth atmosphere (see, for example, http://www.sciencedaily.com/releases/2002/12/021209070904.htm).
So, it is entirely possible that if a person could have stood on the early earth after the evolution of life, they might not have seen the sun and other heavenly objects.
As for as trees and seeds that are mentioned in Day 3, not only do these organisms require direct sunlight, it is entirely unacceptable that they exist in the Archean period. However, again, Hebrew and the way the scriptures were written is very permissive in this interpretation. There are many instances in the scriptures where the 'first event' is what is shown in the chronological sequence, but along with the 'first event', all the later occurrences are grouped together in the chronology of the 'first event'. That is, in this case, the creation of 'basic life' is rightly placed before the elimination of the greenhouse gases that block the sun's visibility, but the Genesis writer includes the entire description of 'basic life' which includes plants, trees, grass, etc. An example of this chronology 'mishap' is Gen 2:17 versus Gen.5:5. In Genesis 2:17 it says that Adam would surely die the day he ate the forbidden fruit, however in Gen.5:5 it says he died 930 years old (i.e., after bearing children, etc). Now, someone could say this is a contradiction, but there is no way that the author of Gen.2:17 would have thought that Adam was going to die the day he ate the forbidden fruit since it would totally contradict all the things that happen in the Gen.2-3 story about being pushed out of the garden, etc. So, the correct interpretation of Gen.2:17 is that the "day you eat of it you shall surely die" is that this 'day' would commemorate the timeframe when man could not eat from the fruit of the tree of life, which would have given man immortality. This is basically the same interpretation needed for Genesis 1 where the commemoration date showing the origin of something is earlier than the life of that 'kind' could be seen as happening much later.
I realize that this is 'spin' and it makes no sense to those who would prefer to see Genesis as a made up story, but be that as it may, this particular 'spin' is consistent with Hebrew and consistent with many other places in the Hebrew scriptures where the real interpretation is confusing to those who read modern pieces of literature and are not accustomed to the zig-zag of the Hebrew scriptures. This is not to say that there are no contradictions and inconsistencies in the Hebrew Bible, it is just that in this case, I don't think you can necessarily pin one on the text.
"And besides all that, the fossil record suggests that all higher forms of life emerged in a single 5 million year day. That is, evolution was not gradual as the Genesis story implies, or as Darwin assumed."
Again, there are no real dates mentioned in the Genesis story other than 7 'days' and 7 'nights'. This is clearly a reference to the work week and layed out a justification by the Hebrew priests to impose the requirements of the Sabbath on the workforce so that the priest's could maintain the priesthood (i.e., the Sabbath was also a day of a community gathering to listen to the priests).
However, it is very clear that each day is significant as a commemoration day. In other words, one could interpret Genesis 1 as a week that is 7 consecutive days, OR, one can intepret Gen.1 as a string of 7 days (or week) that are commemoration days (or holidays) that are not consecutive. For example, Day 1 could have been a commemoration day on/about 4.8 billion years ago (i.e., commemorating Sunday - the day of the Sun), Day 2 could have been a commemoration day on/about 4.5 billion years ago (i.e., commemorating the formation of earth), Day 3 could have been a commemoration day on/about 4 billion years ago (i.e., commemorating the origin of life on earth), Day 4 could have been a commemoration day on/about 3.5 billion years ago (i.e., commemoration of the visibility of the universe to the earth), Day 5 could have been a commemoration day on/about 3 billion years ago (i.e., commemoration day about the first Proterozoic life - 'sea life'), Day 6 could have been a commemoration day on/about 400 milliion years ago (i.e., commemoration about the first amphibians - 'land dwellers'). Day 7 could have been a commemoration day on/about 5 million years (i.e., commemoration day of the completion of the major biological life developments on earth).
Now, as I said, these dates of commemoration doesn't mean that all things were chronologically completed, rather it means it the processes started on the commemoration period and can even overlap all the other processes commemorated earlier or later in the Genesis 1 chronology (in the sense that the "day you eat of it you shall surely die"...). As in my example, Adam 'died' the day he ate of the forbidden fruit, but his actual death was 930 years later. The eating from the tree was a commemoration date representing his death in terms of a general concept of mortality.
So, whether people want to treat Genesis as meaningless text from a bygone and primitive era, or as inspired text from a God who knows a little something about something, the text of Genesis still allows an interpretation that is consistent with evolutionary theory and modern planetary science.