In Start Trek : Nemesis when Picard, Data and Worf go to Kolarus III to find the source of a signal, they found a disassembled android. Since Shinzon actually intended Picard to find the android, why was it disassembled and buried? Also, who attacked them while on the planet? Were they of the Reman race or where they the locals of the planet? Shinzon wanted to meet Picard so I don't think he had intended for this to happen.
Question 1: no canonical answer is available. Logically it can be assumed that B4 was disassembled to make the discovery less suspicious: a complete, intact android being found would raise questions, especially when it's common knowledge that that Soong dismantled all of his prototypes (at least it's common knowledge to people with any experience of Data's history - where Shinzon may have got this information is anyone's guess).
Ultimately, Question 1 highlights one of many inconsistencies in what is a rather poor script with many plot holes. The basic, unhelpful answer is "it was in the script". Sadly, there doesn't seem to be a canonical reason.
Question 2: Kolaran natives attacked them. It says so here on Memory Alpha:
However, just as the searchers find the final piece, they come under attack from Kolaran natives in vehicles of their own, so Picard drives the Argo back to the shuttle while Worf mans the phaser cannon.
