Questions on David's order to kill Yoav

Question

When David was dying, he gave a final speech to Shlomo Melachim I 2 . There he tells Shlomo to kill Yoav and Shimi ben Gera.

1. Why are these his final instructions in the first place? I expect a mafia don to give kill orders on his deathbed. From a person as righteous as David, I expect more spiritual instructions. Granted, David was also a general and a war-time king.
2. The reason he gives for killing Yoav seems to ignore some more major reasons to be upset with Yoav. Melachim I 2:5 David mentions Yoav killing Amasa and Avner, but not killing Avshalom or the people with Uriah, both of whom David explicitly says not to kill. So why mention Avner & Amasa, but not Avshalom?
3. The reason not to kill Shimi ben Geira is listed, but the reason not to kill Yoav is not. Why didn't David kill Yoav before this?

Answer 1

I may have an answer for #3

In the first chapter of Melachim we are told of some prominent people who were not part of in Adoniahu's coup

"And Zadok the priest and Benaiahu the son of Jehoiada, and Nathan the prophet, and Shimei and Rei, and the mighty men, who were with David, were not with Adoniahu".

If the Shimei here is the same as Shimei ben Gera, then Solomon might think that Shimei was one of his supporters. David quotes the reason why to kill him to tell Solomon to kill him despite his apparent loyalty now.

Answer 2

Answer to #1 - read either Rash"i or Rada"k who agree on a general theme regarding each of the people David mentions. He states that Shlomo should not kill them immediately, but each of these people, by their own behavior, will eventually perform some action that requires being killed. In fact, each of them did just that, eventually.

The general point is that each of these 3 people did something at the original time that was rebellious against the king. The king is allowed to kill someone who rebels against the throne. For various reasons, David did not do this, so he commands Shlomo to "finish business."

I am surmising, though, that a new king, perhaps cannot execute someone who was rebellious against a previous king and was not executed then. I.e. - the execution status is not "inherited". (Something I have to check in Ramba"m). Regardless, see the above explanation, which was David's intention.

Answer to #2, heard from my Rav when we were studying Melachim:

David didn't mention that Yoav killed Avshalom because that was actually a benefit to Shlomo, at the end. Had Avshalom not been killed, either he may have succeeded in killing his father (David) and / or usurping the throne, then (which was his intention), or he would have tried doingthe same with Shlomo, now. Either way, it would have been less likely that Shlomo would have been king.

The point is, that David intentionally, didn't mention Avshalom being killed so as not to put any positive thoughts in Shlomo's head, at least not directly. (We can assume that the wise Shlomo, knew this angle, anyway.)

I believe that Rash"i may mention this aspect as well.

For #3 - I have to explore further. Offhand (Guess), there may have been a tactical reason to spare Yo'av at the time. I have to read Shmu'el, again, to recall what happened.