For anyone that's renting I recommend doing some sort of cabinet grow that will blend a little better than a humming tent.You can do a cabinet build and just have a large floor fan nearby and turn it on when you need to "disguise" the sound for an inspection or maintenance.
I'm working on a wooden cab, it's currently not the prettiest thing yet, but the next version will be designed according to eye appeal, better stealth as well as efficiency. It's possible to run a 400w in a cabinet with an adequate setup and using a perpetual harvest you could, as the above poster said, be harvesting every couple weeks, or set it up to harvest however often you want.
I don't think I will ever do the autoflower thing, or aim for a 1 week harvest (not unless I have a bigger grow space someday). I'm only planning to do 6 "cycles", with a harvest every 2-3 weeks (depending if I do a sog or scrog). I am using the simplest hydro method available, and cheapest, hempy buckets. I went with coco over perlite though for it's ability to retain moisture so I was less worried about plants drying out too quick before I could save them. Since I switched to the hempy bucket I have seen an huge increase in growth over the old "container with holes in the bottom for drainage". I would not recommend soil, personally.. But that's just my preference. If you do go that grow, please do it right. I think they call it super soil grows or something? I was reading about it on another site a little but didn't interest me.
Edit: Oh, and co2 does help plant growth but I find just spending time in the same room as the intake will provide a decent amount of Co2.. The co2 levels in my room with my windows closed gets up to about 1200-1400ppm in a relatively short time span. If your grow room is separated from society though, then yes you might want to consider supplementing it somehow as another poster said.