peat moss? or sphag? long fiber sphag looks like... well it's loose and furry and stringy and beige ish to light green. if your plant is actually in peat (fine brown stuff--sort of looks like coffee grounds) it won't last long; retains too much water. (yes commercial growers have been known to stuff the plant, seedling plug and all, into a pot and sell it.)
check here:
Orchid Photo Identification Guide
and see if you can tell us what kind of orchid it is generally and we can opine from there.
however, as a general rule, bottom leaves do eventually turn yellow. not to worry unless they're doing it in the space of 12 hours or so. also, buds can shrivel and fall off with changes in temps or even changes in condition. no worry, it won't harm the plant.
once you figure out what kind of orchid you have (frankly it sounds like a phal) go here
http://aos.org/aos/orchids/page01.aspx
and pull up the appropriate culture sheet; it's a good place to start on care. if it's a phal in long fiber sphag, stick it in the sink and pour water through it and let it drain; wait until the top inch or so of sphag is warm and dry again before repeating. (yup, stick your finger down in there.
)