Rabbi Yaakov Lehrfield of YISI said the following ideas in his shiur before Shacharis on Shabbos:
The way that we know that the dying stopped in the midbar is because when Miriam dies it says she died and was buried. Up till that point the protocol was being buried first and then dying (or not).
When the water was provided via the rock it says that it was water for the people and for the animals. We learn from here that a person should drink first and then give his animals to drink. We learn from the pasuk in Vehaya Im Shamoa that we should feed our animals before we ourselves eat. Rabbi Lehrfield suggested that since people usually eat on a more than regular basis they should feed their hungry animals first. But people often dehydrate and don't drink as much as they should and should therefore drink before giving their animals to drink.
Chazal say that we learn from the episode of the hitting of the rock that one who assists in doing an aveira is held responsible like the perpetrator of the aveira itself. The idea is that we learn this from Aharon. But how was Aharon to know that Moshe was going to hit the rock that he could have been expected to stop him? This may be why the Torah goes out of the way to say that Moshe hit the rock twice. The first time Aharon was taken by surprise, but perhaps the second time he could have/should have known it was coming.
The Baal HaTurim seems to say that the punishment fit the crime, regarding the hitting of the rock. Moshe did not sanctify G-d's name and therefore was not allowed in Israel, the land in which all existence is in essence a sanctification of G-d's name.
Tradition has it that when it mentions the Canaani in this portion they are located in the wrong place. Tradition has it that this was actually Amalek posing as the Cananites. They learned the language and pretended to be them. They had a choice - to dress like them or take their language. The question is, why not change both? The answer suggested is that if you change both your language and dress you change and become someone else. This is when people get serious about religion they change (or people influencing them have them change) two things, attire and way of speaking. This is why a major part of Shabbos is the altering of these two realms.