add to dictionary
on the top of the screen you should see a button that says "tools". click on it. under it there will be 2 options, spelling and grammar and research. click on spelling and grammar. ta da!
Yes. When the spell checker finds a word it does not know, just click on the Add to dictionary button.
Yes. In Word, choose the Tools menu, then Options. Click on the Spelling & Grammar tab, click on the Custom Dictionaries button, then Modify to see the list of entries.
by clicking the File tab and clicking the Options button.
Yes. This will not ignore later instances of the spelling, when it may not be intentional.