visa extension: very confused

sorry if I repeat already exhisting post!

I need your help/

I came to Canada as a student almost 2 years ago.
My study permit (non-degree program) expires in September 2009.

I already applied for perminent residency (as a skilled worker) in 2008 october, and a received a reply from Buffalo that the documents are received -so now I can track my file online and it says there "in process since march 2009".

I've lived in common law relationship with my boyfriend for almost 2 years already.

My questions is: can i extend my stay?? (i m not goint to study or work right now), i still have student visa till september and a study permit till september as well.

i found this link
http://www.cic.gc.ca/english/information/applications/extend-permit.asp

is it what i should do? ( I am generally confused which FORM to use to APPLY for extension)

if yes - 1 why they ask for the acceptance letter from education institution if i am just changing my condition to visitor under circumstance that i am in common-law relationship? (in the checklist it says - proof of acceptance from educat establishment)

2 what should i indicate in the line "i wish to extend my stay till YY MM DD" Huh

(they give choice?)
is there any chance to ask for multiple-entry visa?

thank you for any help!