I've aliased vim -> "vim -p" which opens files into multiple tabs when passed as arguments.

I've rebound the arrow keys to switch and move tabs and buffers.

* up/down: previous/next buffer

* left/right: previous/next tab

* shift left/right: move tab to left or right

    inoremap <Up> <esc>:bprev<cr>
    inoremap <Down> <esc>:bnext<cr>
    inoremap <Left> <esc>:tabprev<cr>
    inoremap <Right> <esc>:tabnext<cr>
    noremap <Up> :bprev<cr>
    noremap <Down> :bnext<cr>
    noremap <Left> :tabprev<cr>
    noremap <Right> :tabnext<cr>
    nnoremap <silent> <S-Left> :execute 'silent! tabmove ' . (tabpagenr()-2)<CR>
    nnoremap <silent> <S-Right> :execute 'silent! tabmove ' . tabpagenr()<CR>

As for working with multiple files easier when vim's already open, it's a combination of Command-T, Buffer Explorer, and NERD tree.