The door was the type that had to be locked when closed. If it was not locked, it did not stay closed.
The door was not left wide open when Knox and Sollecito left the afternoon before (per their information), and they were the last to be at the cottage before Meredith returned home alone. Therefore, it was locked when Meredith arrived home. It has been ruled out that Meredith invited Guede in because she was tired (having been at halloween parties until 6 am - IIRC), probably a bit hungover and had borrowed a book (to prepare for an exam) that she had to return the following day at noon.
There is no evidence to suggest that Guede was carrying a large rock.
When did Knox babysit children ... when she was 14 years old? A lot changes between 14 and 20. The family - even CNN - has been publishing childhood photos of Knox in order to influence public opinion into believing that she's a wee lass. If Guede had a PR company, we would be seeing sweet innocent pictures of him as a child too. The bottom line is that none of the culprits were children when they committed the murder.
Guede was abandoned by his mother. At the age of 5, he went to Italy with his father and, when his father returned to the Ivory Coast, he was adopted by a well to do family in Perugia. He was not a good student, but excelled at basketball. He was not a good worker, but he had his own apartment. Sollecito had been picked up by police for drug possession, but not Guede. Sollecito had been caught with bestiality videos on his computer and had to be monitored because of his abnormal interests. Knox had been given a citation for disturbance of the peace and rock throwing. Much has been done to paint Guede as a bad person prior to the murder, but Guede had no criminal record. When he was discovered in the daycare, which he thought was a squatter's place (according to him), he was non-confrontational. There was no violence in Guede's past.
Curt and Edda Knox are facing slander charges for publicly stating to the British media that Knox was deprived of physically and pyschologically abused for 54 hours. The only source for that information is Knox ... as neither her lawyers nor parents would make that up for no reason.
The evidence against all three culprits was sufficient for a jury or Judge (Guede's trial) to conclude that they are all guilty of murder. The evidence against Guede is not stronger than the evidence against the other two. However, if we eliminate all the forensic evidence, then the evidence against all three of them is equally weak. Guede admitted being in the bathroom at the time of the murder and the evidence proves that he was in the bathroom at some point.
Regarding the 54 hours:
"But Knox's lawyers say the Seattle native only confessed to being at home the night of the murder after nearly 54 hours of intense interrogation without a solicitor or interpreter. She later retracted her statement."
http://www.dailytelegraph.com.au/amanda-knoxs-lawyers-confident/story-fn6e1m7z-1225992691127
"Curt Knox said, "Amanda was abused physically and verbally. She told us she was hit in the back of the head by a police officer with an open hand, at least twice. The police told her, 'If you ask for a lawyer, things will get worse for you' and 'If you don't give us some explanation for what happened, you're going to go to jail for a very long time.'"
http://www.cbsnews.com/stories/2011/02/15/501364/main20031993.shtml