New and wondering if my orchid is healthy

[meghan]

Hi there,

I'm new to the whole "actually attempting to keep a plant alive" and I'm looking forward to caring for my orchid and possibly others in the future.
I have done a lot of reading online so I'd like to think I am fairly well versed on the basics.

I bought my orchid (it's a phalaenopsis) only a few days ago and at the store (IKEA) I looked around a lot at different ones for obvious signs that it was or wasn't doing well... I thought I got a healthy one but I later noticed the underside of one of the top leaves has some brown discolouration, I'm not sure what it is as it's not black or big spots? I did make sure it got some indirect sunlight from a west facing window (it's winter here so there is not much light so I'm not too worried about sunburning the leaves). There was the same brown stuff around the rim of the leaf but after exposure to light it has faded quite a bit. The flowers are holding up and one of them even opened and is about half open, which is exciting.
My bedroom tends to alternate between temperature extremes since it is in what used to be an attic. I have a space heater though and I'm not letting the temperature drop below 17-18 celcius at night and I'm trying to keep it around 20-21 celcius during the day. I don't know what to do about the humidity and I don't know how to check what the humidity is in a room.
I kept the orchid in the plastic container and the moss was pretty damp when I bought it and still is so I haven't watered it. I can't see the roots very well but as far as I can tell they are green.

I took some pictures and will post the links:

- This one is the full view of the whole plant:
http://i44.tinypic.com/35d2gwk.jpg

- This one is the underside of the affected brown area leaf:
http://i44.tinypic.com/35mr2mb.jpg

- This one is a another stem branching off the main one(more below):
http://i42.tinypic.com/28rkrb8.jpg

- This one is just the leaves:
http://i42.tinypic.com/24l38u1.jpg


So basically my questions are:

1) What is this brown discolouration? Should I cut off the affected parts... it is mainly on the one leaf but the leaf under that one seems to be starting to get it as well... and put cinnamon where I cut?

2) Should I do something about humidity? For instance I could boil some water and bring the phal down in between waterings to expose it to the humidity?

3) As for the flower stem branching off, it might be hard to see in the photo but it is a bit of a brown colour, is it dead? & would it be better if I just cut it off to save the plant energy?

4) The moss seems pretty tightly packed so after the bloom is over should I switch mediums? Or am I being paranoid about root rot?

I think that's it... any help and additional pointers are greatly appreciated
Thanks for taking the time to read