I think most safe have holes in the bottom so you can bolt them directly to the floor. If you have concrete then you just need to drill holes and place anchors in the holes that will accept the right size bolts and your good to go.
Also weight is your freind get some lead and put it in the...
I find if the ends are dark it probably means burnout is going to occur soon.
The flickering only occurs on mine when the temperature drops into the forties.
Do you mean coils on the interior of the structure or exterior. Exterior coils are becoming more and more popular with rising energy and can be made at home, although not as effecient as some commercial stuff thats available. As for interior whatever means you are using to heat the space would...