Oxyclean will impart the metallic taste especially if it wasn't rinsed thoroughly. When cleaning your rinse water should always be hotter than the treated cleaning water.
Have you read any of the threads on brewing or picked up book? No offense but out of all the questions you've asked it seems to me that you don't want to actually understand the process you just want to do it.
There are a ton of great threads and processes you can follow, I know they've been...
So let me get this right:
You put the whole can of extract still in the can into boiling water?
In a separate pot you boiled water.
Added both to the bucket and put all of the fermentables in there.
Topped off with Cold water, stirred a little bit and pitched the Yeast.
I stir throughout my mash and my beers end up clear. It seems to me that you aren't vorlaufing enough and thats why you're still getting grains in the BK. Also, make sure the False bottom is stuck to the bottom, sometimes it'll lift up and cause a big mess.
To pre-heat your Tun simply use your mash volume. Preheat to about 175/180, dump into MLT. Let rest for 10 mins to stabilize. If still too hot, stir to reach strike temp(around 165-160). Dough-in wait 10 more mins take temp and adjust if necessary.
I shrink wrap 1 rare earth magnet and use a hop sock. I then use the other rare earth on the outside to hold it in place.
by rare earth, I mean HD magnets.
I calibrated mine with the water I use to brew.
1) Drew a sample for my hydrometer and took a reading.
2) used same sample for refractometer.
3) entered into beersmith for calibration.
If you're going to use it for the FG you need the OG to account for the alcohol. It will always be off...
False Bottoms are fickle when it comes to draining rates. Sounds to me you compacted your grain bed and gravity locked the FB. Stirring helps but can cause clarity issues. In the future slowly open the drain and never run it full-bore.