Backup and analyse

I could not easily find answers to these simple questions.

a) Does VACUUMing ( with ANALYSE ) in effect perform a file consistency 
check on the database structure as a side effect?

b) Is it ok to VACUUM while the database  is alive and active?

c) Can I backup via pg_dump while the database is alive and active and 
have the backup consistent to the state the database was in when the 
backup started?


I'm 99.99% sure the answers are yes for all of these but I'd very much 
like to have it confirmed by somebody who _really knows_.

-- 
Sincerely etc.,

 NAME       Christopher Sawtell
 CELL PHONE 021 257 4451
 ICQ UIN    45863470
 EMAIL      csawtell @ xtra . co . nz
 CNOTES     ftp://ftp.funet.fi/pub/languages/C/tutorials/sawtell_C.tar.gz

 -->> Please refrain from using HTML or WORD attachments in e-mails to me 
<<--