I was watching DBZ again on NickToons and I was wondering why the hell Koron (that white talking cat) was not prepared to give the gang any sensu beans before their fight with Nappa and Vegeta. They had like what, nearly a year to prepare for this ?
Also, Goku was a fool to split his last sensu bean in half to give to Krillan and Gohan. He knew Kaio-ken would cause harm to his own body and he ended up having to use it a lot, once even on Nappa.
If he had kept half a sensu bean for himself, then he could have obviously not burnt out his body as much using that technique. Another thing, Goku could have given himself an advantage by using Solar flare on Vegeta before going into Kaio-Ken.
One more thing. During the Frieza saga, when Vegeta and the others were fighting Freeza, it never occurred to Krillin or Gohan to get Dende to Frieza's spaceship in order to take out Goku from the healing chamber and use Dende's powers to heal him faster.
You have to remember that Toriyama was writing on the fly, he is self-admittedly not a good pacer. So there's always going to be little plotholes about the characters' actions.
That said, a lot of the plotholes you describe are just the characters making mistakes or being themselves, i.e. Goku constantly sees every fight as a chance for a challenge, even when the Earth's at stake.
So that being said...
1. Korin the cat can only grow so many Senzus; they take time like any plant. So presumably they hadn't grown enough by then.
2. Goku will ALWAYS think about his friends first, even when it's dangerous for himself.
3. Almost every character in EVERY battle forgets about the usefulness of abilities like the Solar Flare or Kienzan (DESTRUCTO DIIIISC). All the main villains, including their underlings, can have the same question about why the heroes didn't blind them and cut them in two in that brief moment. It's just Toriyama writing to ensure drama instead of clever battles that end fast.
4. Again, Toriyama just forgot, but there could be numerous explanations: The characters forgot about Goku at that moment, or maybe the ship was just too far away, or maybe they just didn't have time to sit down and work out a plan while panicking and running so much.