If the bike is new it's quite natural for it to use some oil, as it is settling in. Good oil will change colour quite quickly as it does indeed collect all the smut so as to keep your engines internal parts clean.
Mine has about ten thou of hard use now and doesn't use any oil at all to speak of, as for filling, you just put in a bit at a time and wait a few seconds for the level to sort itself out, easy!
