You can submit a webform for 1-3 and wait for IRCC response. For 4, (ideally) they will ask you to provide that information when processing instead of returning your application.
Now, if you don't want to do that and withdraw and resubmit instead, this is what you should do.
- Submit the withdrawal request.
- Submit the new application(you can do it right after submitting withdrawal) and explain in a letter that you have previously submitted and withdrawn an application and would like this one to be processed instead. Add the reasons for withdrawal.
If your 1st application has already reached the capture stage, you will lose the fees. If it hasn't, the fees can be applied to your 2nd application.
And yes, you can work while waiting for PGWP if you meet the conditions mentioned here.
https://ircc.canada.ca/english/helpcentre/answer.asp?qnum=1181