e - move forward the end of the word
b - move backward to the beginning of the word
eb - selects the whole word

% - select whole file
v - enters Select mode - movement will extend the selection, as opposed to replacing it.
v2w - select two words.

t Enter - select from the current position till the end of the line
T Enter - select from the current position to the beginning of the line

; - collapse selection onto a single cursor

p - paste after selection
P - paster before selection

Ctrl-c - comment/uncomment selection

C - duplicate the cursor to the next suitable line
, - remove first cursors

Buffer is a file. You can open multiple files simultaneously.

Space - b - buffer picker
:bp - previous buffer
:bn - next buffer
:bc - close current buffer

Ctrl - c - comments out the text. Or undo it

Let's say you want to replace foo with bar everywhere in the document.

% - select the whole document

s - press s key for search and type the text you want to replace, e.g. 'select:foo<Enter>'

At this point you can scroll through the file and visually check what's highlighted

c - type c for change and put in a new text