Actually if you enter under the visa waiver program you cannot, at a later stage, change status. The waiver program is very strict and you can only change status in the US if you entered on a visa. Only US Embassy's issue visa's not the immigration service so, yes you'll have to go home and apply for the M-1 visa through the local embassy. Your friend doesn't need a visa, she could enter under the waiver program. As for entering the country without a return ticket that's never a good idea simply because it gives the impression to the immigration inspector that you my have the potential not to leave when your time is up. And you did say "clearly I would not be using the return ticket." Tell that to an inspector and you most definately won't be allowed in. Remember every foreign citizen entering the US is PRESUMED to have immigrant intent - that's the wording of the law. So you have to show that your intent is non-immigrant and a return ticket helps enforce that intent. Pre 9/11 immigration was more relaxed but it really isn't worth trying to bend the system now.