Lovebirds do a type of chattering that you described. It’s usually done as affection towards a person, another bird or an object. Birds can get cold, but typically the bird will fluff up the feathers as a way of keeping warm. The chattering is not related to being cold. Parasites are very rare in pet birds that are kept indoors, and the parasites they can get are host-specific. Your body temperature could not support a parasite that gets on birds. There is no reason to be concerned with parasites unless the bird has been kept outdoors for a long time, or has been kept in very poor, filthy conditions. Nail trimming varies by bird. Most of the time, the nails get too sharp before they get too long, so if you handle the bird, it might need the nails trimmed every other month. But for length, most birds only need a nail trim 1-3 times per year.
Thank you for asking Lafeber,