COS from b1 to f1

[osler]

I am near my 5 mo stay under a B1. I am considering to COS to an F1(prep course)., because i am planning to enroll in a graduate school.

1. How difficult is to change status from B1 to F1 (prep course).
2. What other documents would be needed to file the application in addition to the I539, copy of I94,Visa,passport ?
3. Which is better if i added a financial statement from my home country or a sponsor in the US with a I134.
4. Do i need to submit a letter reasoning why i am taking the course ?

I know that the processing time is 2.5 mo, what if i overstayed my i94, would it make a negative record in the case my COS is denied. What are the concequences ?

I did not inform my intent to study at POE.

 

[johnymac]

I applied for a master of Architecture program in US in Fall 2009 and got the admission in Feb 2010. However, I was not sure if I was going to accept the offer since I did not like the school that much. In April 19th I got a three-month B1 visa for a conference related to our family business (Milling industry) , totally unrelated to my academic field of study (Architecture). When the conference ended after a couple of days of my arrival, I visited the school and actually liked it. So I made a deposit and asked for an I20 and it was about two weeks after my arrival to US. Now, I have my I20 in hand but I was told that I better not apply for a change of status now since it is too early and USCIS my consider it a misrepresentation of my intention to come to US while applying for B1 visa.
Here is the question: Does the issuance of I20 mean that some kind of documents has already been send to USCIS by the school? If this is true does it mean that USCIS already knows about my intention to attend school even if I apply for a change of status later (probably after 60 days of my arrival)?