Thank you for your thoughts. I'll start out by saying that you have some good reasons to believe what you do.
Doesn't it strike you a little peculiar, though, that ever since the beginning of time people have believed in a literal 24 hour day creation period, whilst, only until recently has the long-day theory been advanced and popularized?
As far as the passage, you mention that most Bibles footnote it as became, I would assume that there is a debate here based on textual science. So I would guess that the debate is valid. I don't, however, think you can, out of this, pull an absolute claim that this word has been hijacked for centuries and that the passage's presumed established meaning throughout history has been masked by the recent translations. The Bible has many words that can be translated one way or the other, as far as sense and tense and other grammatical situations, similar to this situation. You cannot absolutely conclude, based on the textual evidence alone that became is the proper translation.
2 Peter 2:4-5 (NASB) 4 For if God did not spare angels when they sinned, but cast them into hell and committed them to pits of darkness, reserved for judgment; 5 and did not spare the ancient world, but preserved Noah, a preacher of righteousness, with seven others, when He brought a flood upon the world of the ungodly;
All I see in these two verses are the fall of Satan and his angels and the Genesis flood. There is no indication of an earth inhabited between eternity and Gen. 1:1.