Do I need a visa stamp?

[mzdef]

Hello, 

I feel stupid for asking this question but please bear with me.

I'm a Canadian citizen (born in pakistan) who did a J1 residency in the US. I applied for H1b and J1 waiver and was approved for both and have started a J1 waiver job in the summer already. The thing is I haven't travelled outside the US in a long time so the only thing in my passport is the old I94 from the J1 days as well as a new I94 which I received in the mail (I guess for H1b status). I don't have any sort of visa stamp except for my old J1 stamp years ago.

My question is do I need to travel outside the country (Canada would be most convenient obviously) and get a H1b visa stamp at the border? Will there be a problem that I've waited this long? What documents will I need? Is it a problem that I still have my old I94 in my passport? Does this affect my 3 year minimum waiver requirement?

Thanks and again I should know this stuff but I'm clueless.