Hello tifanjo and welcome to the thread!
Hopefully we can help you some.
Well here is the link to the forms you need to complete and yes it is the IMM 1249 form.
http://www.cic.gc.ca/english/information/applications/visitor.asp
You will mark C for "initial work permit". Be sure to include the document checklist, receipt for fees, sign it, date it and include all the the documents it ask for on the checklist. If you don't have a representative then you do not need to include that form and also if you are not in a common law relationship, you do not need to include the statutory declaration form. However as stated be sure to include the document checklist and documents on the checklist with it.
You can write on top of the forms "Do Not Process Until Approval In Principle". It will keep your status valid until a decision is made on AIP. Since AIP is currently taking about 9 months to get after they receive your application, this is how long it will take to receive the work permit. You will not receive it before then or until they approve you for AIP which like I said is 9 months from the day they receive your application. Also, get tracking on your application with a courier service because they will not mail you anything letting you know they received your application. You will not be able to know whether they received your app until they begin processing it which usually isn't until 2 and half months to 3 months after they receive your application.
And yes, include the OWP with the PR application in the same envelope. Be sure to mail and make sure it is received before your current status expires. If you do so, your status will remain valid for the duration of the time and you will not have to continue extending your stay. When they approve you for AIP (meaning they deemed your relationship genuine and your sponsor is an eligible sponsor) after 9 months you will receive a couple of letters and with the letter will be your OWP. The OWP from what I hear are normally valid for 1 year. This will give you plenty of valid status until they finalize your PR app which can be upto another 9 months after receiving AIP and OWP. They will contact you when it is finished.
Please let us know if anything is confusing or if you have anymore questions. We will do our best to help you. Also good luck on your application!