In order of politeness starting with most polite:
otaku
anata
kimi
omae
anta
http://japanese.about.com/library/weekly/aa100700.htm?nl=1
Strange that 'otaku' is the most formal way, huh?...
Depends on writing (kanji) and where it is used. It can be 度 a counter for degrees in general usage, as well as a counter for 'times' as in once twice etc. E.g. 'sanbyaku rokujuu do' would mean...