what help to I need

If you hire the Ikea installers they should be able to do the whole job. It gets a little tricky as you do not know what installers you will be getting. Some are good and like everything else some are not so good. You can hire a gc to do the whole project just make sure they have experience with Ikea. If they do you should be able to customize the cabinets to fit in your space.

Thank you for your response! So the IKEA installers will be able to sand and finish the floor as well as paint?

I would go with these folks - http://turnkeydandc.com/

Make sure you know your co-op's rules. My prewar building requires going back to the risers for plumbing and electricity when renovating.. Not so sure I'd trust Ikea to handle everything, from DOB permits to understanding how to deal with a Manhattan co-op's building management.

That's actually a sane requirement, but it does shift the cost of replacing "inside the wall plumbing" from the Coop to the shareholder.