#1. portraits are done in landscape when there is a reason, something to balance, negative space, other centers of interest. In this case, there's lots of room on either side but you've cut the top of your head off.
#2 selective color is something done when people new to photography discover they can do it. It is rarely interesting or successful and generally marks someone as a beginner.
#3 Damn close. Nicely focused, your fingers look good. What spoils it for me is the large meaty OOF chunk on your left. It is unclear what it is and it looks out of place to me.
Conversions are OK. A bit muddy but not bad at all.