Well, you can not ask to transfer a file to other visa office (you can ask but they will probably say "no"). I read here before that someone asked for file to be transferred and it was approved. I'm not sure if i believe this....
Files can be transferred to other visa offices only if CIC wants to because of "program integrity", only if it helps them to process the file because of a local investigating experience or local knowledge. Remember, immigrating to Canada is a privilege and not a right, they can set the rules and they can choose to follow them, as they SHOULD.
If they ask you to come for an interview and you don't show up (regardless of the reason why you failed to show up), guess what? your file will be denied. As far as a phone or skype interview, it is a their discretion, but i would think that they would call you first instead of asking to come for an interview, again, this would be easier for them to do instead of an in person interview. There must be a reason why they want you in person.
Below, is a copy and paste out of CIC regulations about files transfer, read last paragraph carefully:
"Processing offices may transfer files at any stage for reasons of program integrity.
Program integrity includes issues related to local knowledge, such as the ability to effectively evaluate documents: knowledge of local security and criminality environments; or familiarity with business practices and procedures.
Progam integrity also includes improving program efficiencies. For example missions may be asked by National Headquarters to transfer files in order to improve processing times where there are insufficient capacities to process the volume of applications at the mission or in the event of special circumstances (political instability, natural disaster, etc) . This not only helps the department in reaching its objectives but the applicant also benefits from faster processing times. Other factors may be taken into account when evaluating the impact of a file transfer on program integrity.
Processing offices are not required to transfer files for any other reasons. Such reasons include cases of applicants who comply with subsection R11(1) for the specified visa office, at the time the application is received at the CIO, but subsequently leave the territory of the specified visa office. In these cases, the original visa office should proceed and process the application as usual.. Leaving a visa office's territory alone, may not warrant a file transfer. In this case, if an applicant requests a file transfer, the visa office should inform them that the application will not be transferred."