Making sure you have well written reports with 0 grammatical issues on a consistent basis.
It's really not a secret at all, every time you have a shop approved it tells you how many points you are receiving. It changes as you go up in reputation. Your self assign limit goes up every time you level up, this information was also given to everyone. What is required to obtain badges is clear on the badge page as well.
You can, that's why they suggest you start on Thursday as a new shopper so that you have a couple days to get it done.
Yes, depending on the job it will tell you the frequency in which you can complete them like every 90 days ect.
There is no making mistakes with Field Inspections like there is with these shops. If you mess up a shop, you can always go back and add something. The field inspections they offer are overseen by the FDA so only do them if you are very detail oriented because if you mess up, you'll have to answer to them. You also are scheduling to meet people often times in their homes so make sure that sort of thing doesn't freak you out. That being said, I love field inspections, it's one of my favorite contractor gigs.