if i were you id go with manual assuming you have an experienced person taking the measurements. im an exercise physiologist and even though there are electronic ones and other modes of testing BF% the tried and true method is with manual calipers
no you can the sites your self , also depends on what sites your using. for male you should do ab, thigh, chest and if you have some one doing it for you a subscapulae site would be good as well. the more sites you do the more acccurate the BF%
Well.. in reality.. it's not possible to accurately assess your bodyfat with calipers by yourself. If your body/skin are not completely relaxed, fat displacement takes place, so the test loses validity. Of course you can get a general idea.. but that pretty much defeats the purpose of buying a real set of calipers. Just get the Armron or Tineda (I believe that's how they're spelled) scale. Those will give you a general estimate of your bodyfat % that's quick and easy to keep track of.