Well, i would like to carry out functional (expression based) metagenomics. However, I am very much new to this field. I have a series of doubts which i am unable to clear myself through books/papers. Thus, i need your guidance...

1. Most of the papers on expression based metagenomic deals with 40,000 to millions of cloned libraries. I assume that the creation of such huge metagenomic library would need robotic colony picker and it wont be possible to do manually. Please rectify if am mistaken.
2. Instead of creating the library itself, if we plate the transformed cells into selective media, would not it be a better idea since only the clones with the gene of insert would grow in the selective media. Thus, we would save time and money and also bypass the need of robotic colony pickers for making such huge library.