I remember feeling this way! so will do my best to help!
bathroom for baby
don't bother will special baby oil etc, apparantly it dries babys skin out further i used olive oil and sorbelene and my DS (Still do) and it works wonders on dry skin and leaves them feeling lovely and smooth.
I wash him in QV bathwash i used to use a "special baby one" but found it dried his skin too much. I think u can only get QV from the chemist.

Medicine Cabinet
i didn't have much in this for the first few weeks as you can't give a new born much anyway but i made sure i had a thermometer and later i bought some childrens panadol (just before his needles i think) so sorry not much help here!

Nappy Bag
Nappies obviously lol! and some nappy sacks so the dirty ones don't stink your bag out!
A towel or mat to change bub on lots of spare bibs and clothes
Some wipes for face and bum!
as for nappy cream i was told to get a zinc based one only as they form a better barrier than ones with castor oil mixed in i use one called Desetin and i think u get it from the chemist also. but have also used curash and it has castor oil in it. or u could just use plain old vaseline my MCHN tells me it is just has good as forming a barrier but not as soothing on a rash. so its more of a preventative i think!
Oh and if you're planning on using a dummy make sure u have a spare in the nappy bag as well you never know when u might need it!
Hope this helps a bit
Good luck and happy shopping!