Yes, my understanding of paph's is that while they like moisture they also want quickly draining medium. Moss would therefore not be suitable for them. If you need to purchase medium and can't find any stores that carry paph specific mediums, you might try RePotme.com. I use their mixes and really like them.
Well, I'm afraid that's kinda up to you. I grow mine in bark because I don't have the conditions in the house to allow the moss to dry quickly enough and my limited experiences haven't been too great. Just be careful with moisture levels, only water when needed, make sure the moss doesn't get too compacted etc. There's lots of info on here in various threads, so you can have a look and see what others in the US say.
yes defenatly clear the moss from around the base of the plant, rot is very common in orchids. Be careful you don't overwater it . I'd actually repot it once the flower has finished and check out the roots and repot into a bark/perlite mix for better drainage. Moss is just harder to grow in for beginners i think.