Definitely not texmf-dist. Sorry if my previous post was confusing. I recommended to *look* at texmf-dist, since that's where most of texlive stuff is installed, hence most of the directories that are ever used are there. So you can get an idea how the tree is structured.
As for your own stuff, texmf-local is the tree to use if you want to make the packages available for all users and have admin privileges; ~/texmf is the tree to use when you want to add packages just for yourself (or you don't have admin privileges). All those trees have the same structure; you can think of them as 'overlays':
for instance, if a tex binary looks for a file, say harvard,sty, it first looks in ~/texmf/tex/latex/* (all subdirs as well), then /opt/texlive/texmf-local/tex/latex/*, and finally in /opt/texlive/texmf-dist/tex/latex/*.
[Note: texmf-var is intended for automatically generated files - like formats, pk fonts and such.]
\arraystretch is the command that sets the height of tables - useful hack to make an empty table cell taller
\arraystretch
scales the height of the cell by a factor. As in the above codes, the spacing of a row in the table is 2 times the default.