I was never told to get any kind of "pressure clothing." I'm not sure what that is other than something like a sports bra or the like. The last thing I wanted on any of the areas of surgery was pressure. In fact, I remember being quite fearful of anything getting near my incisions/scars, aside from loose clothing, bandages and pillows.
After my sister had her implants (due to cancer, twice), I remember she was told to wear snug bras/sports bras, but my docs said I don't need to wear anything.
Comfortable clothing was anything loose and far away from tight-fitting clothes. During recovery time, loose sweat/flannel pants and oversized t-shirts were wonderful. Anything loose, soft, etc. was the best.
As for the iv in my neck...I have no idea why that was there. I'd even have to look at the videos to remember when they took it out. I imagine it was another method to pump me full of pain meds, or perhaps a quick access point in case of an emergency. Sorry I can't answer that one. I'll ask my husband; maybe he knows.
I hope this helps, although I don't think I've provided much information. I'm sorry you have to go through this. It's a long recovery, so just be sure to take it easy and don't be afraid to ask people for help. I hope you have a good support system in place with people who can help with meals, kids, driving to doc appointments, etc. Anyone going through this needs all the support they can get.
Good luck! Please let me know if I can answer any more questions. By the way, where are you having this done? Are you in the SF Bay Area? Going to UCSF?