Actually, you can use "etc." The official APA style blog wrote a post about using Latin abbreviations. "Etc" does not need to be spelled out. Put a comma before if used to end a list of at least two other items.
Use one space after a punctuation in APA format.
Sources are never considered outdated for APA writing.
An APA formatted paper is writing the paper in accordance with the APA guidelines.
APA is American Psychological Association.
250 words or less is suggested length of an abstract in APA style writing.
No, you can't number sentences in APA style writing.
APA stands for American Psychological Association and is guidelines for writing papers.
Acronyms are allowed in APA.
Acronyms are abbreviations allowed in APA style writing.
No, APA style is used world wide.
APA style is certainly a good choice for most appropriate in technical writing (I am an engineer and that is the style I had to use). It will depend on the requirements of the person or institution that will be the final authority on what style is required for your work.