The Japanese "If"

It seems like the Japanese are big fans of synonyms!

Dattara
Ano hito ga ikun dattara, watashi wa ikanai.
(If he's going, I'm not going. NB: Cannot find "dattara" in dictionary, it must be a conjugation, but of what?)

Nara
Anata ga so iu nara, natto o tabete mimasu.
(If you say so, I'll try some beans. NB: Tabete mimasu? Eat and drink?? EDIT Mel Tan: tabetemimasu means 'try to eat' or more literallly, 'eat and see')

EDIT zu31g:
like cause and effect
for example
gakkou ni ittara, jyugyou ga ukerareru
if u go to school, you can take classes
tara has to imply cause and effect
me: i see
nara is not
nara is more like "if this is abt XXX"
something like that
kono mise to iu nara, ramen ga oishisou datta
me: wicked
i will put this up
if you're talking abt this shop, i heard that the ramen is delicious

Moshimo ... naraba
Moshimo hoka ni jouhou ga hitsuyo naraba ...
(If you need any other information ...)

Kadouka
Kare ga sansei suru kadouka wakaranai.
(I don't know if he will agree.)

EDIT Mel Tan:
'kadouka' should be read as XX-ka, douka, XXX
'ka' basically makes a statement into a question
so 'sansei suru ka, douka, wakaranai'
literally means "agree?, how?, don't know"

Tasuke hitsuyo to suru ...


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Additional stuff from Mel Tan:

koto in some cases also denotes experience
like when we say nihon e ittakoto ga aru.... basically what we're doing is making iku, a verb into a noun (i.e. the experience of going)

iku (dictionary form) --> itta (past tense) --> itta koto ('nounification')