I only used Gervin because at the time it's what was easily available to me and is a good all round yeast and has an alight flavour to it. It's the standard go to yeast I believe.
Yeast can only multiply to what resources they have available. If you use 11g of yeast you will get a much faster fermentation start as there's more yeast to multiply. I also dislike having half opened yeast packets and would rather use it up in one go than have it in storage etc.
I used glass bottles and have never had anything explode on me yet. As long as your sure fermentation has stopped you should be OK to add a little bit of sugar to prime and then bottle them.
If you are worried feel free to use plastic ones the first time you do it and then you can always refine.