Depends upon the purpose. If it is essential to maintain the purity of your culture (looking to extract food grade products) it is advisable not to use cement pot. However, in general, I would recommend you not to use cement pots at all since there will be contamination in your culture. Huge glass/ well sterilised plastic basins are advisable.

it depends on the objectives for the study. I can see several that this would benefit but its not of a common practice and definitely not advisable if axenic cultures is required.