Answer T1

From 2006.igem.org

For in vitro recombination, < 10 mM Mg++ and 30% glycerol traps reaction after DNA cleavage and 2 uM EtBr slows strand exchange.

Unclear whether these conditions could be established in E coli.

In http://www.kip.uni-heidelberg.de/chromcon/publications/pdf-files/Rippe_NAR_97.pdf, superhelical density of a 1868 bp plasmid was -0.03, with 80% of plasmids having -6 supercoils.