If IRCC asked about the government job details, they you are most likely going through a comprehensive background/security check which might take years, unfortunately.
You get assessed against many factors, one of them is a travel history. If you don't have one, you need to have stronger points for other factors to compensate lacking travel history.
Yes, you can add your spouse but check your score if it doesn't drop below your draw cut off.
IELTS taken after the ITA but before the submission date is acceptable .
You don't need to get married to apply for PR you can apply as common law partners if you have been living together 12+ consecutive months (some reasonable gaps are okay).
Yes, you can re-enter as a visitor with a valid TRV. But every time you enter Canada you may get reassessed based on your current situation so just be prepared but it's a rare case, usually a couple of questions from an officer and simple as that.