Hi,
would she come as a tourist, and still apply from the outside, how long can she stay with me? The 6 month, or longer?
yes the application would b processed in Vienna (the 2nd part) while she's waiting as a tourist in Canada with you
i'm not in this situation but there are plenty others who are....search a little (outland while waiting in Canada) or start a new thread; from what i know: yes the visit visa is 6 months in general but the officer could put an expiry date for less (probably not considering she's Austrian); after 6 months u could apply for extension but not sure abt the chance of getting it; anyhow, the most important when she comes as a visitor is that she proves that she's coming temporarily to Canada, she shows ties with Austria (house, job), planned approximate departure date from Canada (safer to have her ticket both ways)
in general the ones who can avoid inland they do (others they do it inland because they cannot leave from Canada and come back since they need to apply for visit visa from before and they never get it); the big disadvantage of inland is that in general is slower (check the timelines - inland vs Vienna VO), the applicant cannot leave Canada (in case she is not let back in, the application is lost) AND there's no appeal right....
since she's Austrian, u r part of the lucky ones, u can both easily visit each other and stay with each other for as long as u want (more or less

) while the application is in process
good luck!!