(Hiragana coming when I upload it...)
先輩 SENPAI: Sometimes romanized as 'sempai'. Usually in reference to a student who is older (upper classman). For instance, a 10th grader might call a 12th grade 'senpai'. Often seen in reference to someone who has just 'been around longer' than the speaker. The opposite is 後輩 kouhai こうはい(lower classman).
相棒 AIBOU: 'Partner'. In Yu-gi-oh it is used between the omote and the spirit. It is also the name of that mechanical dog that came out a while ago.
KAA-SAN: 'Mother'. Okaa-san is usually what you have call other people's mothers. Your own mother can be Haha, Hahahue, Okaasan, okaachan, kaasan, kaachan etcetc... depending. <--Mother kanji. The 'kaa' in Okaa-san and the 'haha' of 'hahahue'.
NII-SAN: 'Older brother'. The variant of 'onii-san'. Not NI or ONI, ONI meaning demon :P. <--- the Nii part of 'onii-san'. And the 'ani' of 'aniki' (also 'older brother').
NEE-SAN: ねえさん Is the form I believe Marlene uses to refer to Aeris. (Form of Onee-san, oneechan, neechan... ane/aneue).
lazulisong wins over me :o
Shachou 社主 しゃちょう - company head or leader (I think; that's what sounds closest anyway
(Kanji from wonderful mepwnage lazulisong for all of the above :D)
(If you have anymore questions or phrases/titles, don't feel afraid to comment, I'll edit as we go :D)