1- I never really thought of that... Maybe he has that disease, like in "Jack". It's not that much of a plot hole though, let's asume he was on his what, late 30s early 40s on ROTS? Therefore on his late 50s early 60s on ANH...

2- My answer to that is simple: that particular scene takes a some years AFTER the twins are born. Notice how all the officials on the Super Star Destroyer bridge have uniforms, Palpatine wouldn't have thousands of uniforms just waiting for his plan to succeed.

3- Not really a plot hole or movie question so...

4- The first question: he does recognize R2D2, but he couldn't say anything to Luke just yet. The second question: obviously a plot hole caused by the excess of CGI on the prequels.

5- Apparently not. Not really a plot hole, so let's move on...

6- She wanted him to be named Luke, so what? Not a plot hole at all.