marriage of foreign husband and malaysian citizenship

hi,
i am from iran,and i am non muslim,but because of my country there is nowhere stated that i am christian,( i have my baptized letter ),here i am trying to register our marriage with my GF(sarawakian,non muslim too ) but JPN doesnt help! plus she is pregnent and will deliver soon.
here are my questions.
1)how can we marry legaly here in malaysia? or if we register in singapore,and then bring the cert. here will it be acceptable and how?!
2)how about our baby?can he get malaysian citizenship ?
3)can our son follow my last name with malaysian citizenship?
4) and can i at least get visa as a parent without register marriage?!

please help me as early as possible as we are running outta time .

all your help will be appreciated