Teaching flyspell new words and autosaving files on C-c C-c

[Lorenzo Isella]

Dear All,
Two auctex-related questions again: I managed to turn on automatically
the flyspell mode when editing a .tex file.
>From time to time, it underlines words which it does not recognize,
though they are correct.
Now, how can I teach it to ignore certain words in the text or to add
them to its own dictionary?
Second question: I would like emacs to automatically save the tex file
I choose to compile with C-c C-c without asking me every time.
How can I do that? I thought the key was to add

(setq TeX-auto-save t)

 to my .emacs file, but it does not do what I would like it to do.
I suppose that understanding this will help me to solve the general
problem of giving a yes/no answer automatically to certain questions
emacs may ask me in different circumstances.
Many thanks

Lorenzo