Is life a billion years younger than the sun? What do you base that on? How do you know that is true?
Multiple lines of independent evidence. The Sun's internal dynamics come from our understanding of everything from the largest Einsteinian space-time warping to the smallest quantum tunnelling (the latter finally explaining the Sun's emission spectrum, something classical mechanics never could). The Earth's age comes from radiometry, geology, cosmology, etc.
We don't know how old earth really is exactly and it could be older even than the evidence shows because factors could change it even more than 30 million years.
They could... but it's unlikely. The sheer abundance of independent bodies of evidence means that the probability that the Earth is indeed 4.54 billion years old is exceedingly high - not just 'best guess', but 'almost certainly the right figure'. The data come from two different angles, one lowering the maximum age (it can't be older than 4.54 billion) and one lowering the minimum age (it can't be younger than 4.54 billion). That all this evidence hones in on exactly the same value is called
consilience, and it makes the evidence is phenomenally stronger and almost impossible to budge.
Isaac Asimov penned a famous essay called
The Relativity of Wrong which explains quite nicely the error you're making. Basically, just because scientific conclusions change doesn't mean that they change completely. We've gone from a flat Earth to a spherical Earth, but that doesn't mean we'll next say the Earth is cubical, and then that it's dodecahedral, and then that it's toroidal. Scientific ocnclusions don't jump around willy-nilly, they
refine.
Even great paradigm shifts follow this trend: the changeover from classical to quantum mechanics didn't radically alter the notion that heavy things fall or snooker balls will collide. It
refined the small-scale behaviour, but didn't overturn the major conclusions drawn from the old theory (heliocentrism, escape velocities, accretion disks, etc).
So while, yes, it's entirely possible that all our observations and measurements are all erroneous and just
coincidentally hone in on exactly the same value, this is bewilderingly unlikely.
It is a scientific consensus that we don't know how old the earth is or what life might have been on the earliest surface.
This simply untrue. The consensus has been that the Earth is 4.5 billion years old, and has been this way for decades. What the first lifeform was is still under debate, but only a handful of hypothesis dominate the discussion. Whether bare RNA or polymers in a micelle bubble, we're looking at very primitive biology - it's not going to be a leprechaun. Even in uncertainty, we know the kinds of things it's going to be.
Another factor that can not be ignored. We know that fossil evidence is sporadic at best and that some life forms that were thought to be arriving on the scene through the fossil evidence is found later to refute that time line and it is found that they were present millions and millions of years earlier than thought.
Yes. So? There are limits as to how early life can arise - you won't find primates prior to mammals, nor flowering plants before angiosperms. Exactly when flowering plants arose may be tweaked and refined, but the core order of events remains the same.
That flowering plants are actually at least 240 million years old (something I didn't know, thanks for the heads up

) is ultimately only so much detail. The order of events, plant ancestry, etc, remains unchanged. It's not like we've discovered the first lifeform was a solitary rose.
So we can see that fossil evidence can be at least 100 million years wrong and perhaps even longer.
'Wrong'? What evidence was wrong, exactly? The 140 million year figure is the oldest known fossil, and is the minimum age that flowering plants can be. But there is a maximum age, too - we won't discover 5 billion year old plants, because there were no plants before there was a planet to sit on.
Science is restricted to known in the hand fossil evidence that can be extremely unsatisfactory. One can not claim that the Biblical scenario is not within time frame that "science says" when science obviously is wrong about the time frame by at least 100 million years if not more. It is reasonable to even imagine that life began on earth with plants that even included flowering plants and then all was wiped out except Cyanobacteria. Who knows. We don't have fossils that go back to the earliest time on earth.
Well,
we know. We know the ancestry of modern flowering plants. We know that plants and animals are related by a common ancestor, which must necessarily precede both kingdoms.
Again, your problem is assuming that scientific conclusions are unreliable because they're subject to change. Do you reject the conclusion that the Earth is spherical(ish) because science changes? Of course not.