If you go into your user preferences on the site there’s a spot where it says “Measure in drops or grams.” Make sure that is set to grams. The calculator will do the rest for you. As for flavors, there are two schools of thought on that one. Some people check the box right under “measure in…” that says “use manufacturer specific gravities” while others prefer to leave it unchecked. If it is checked and the spec grav is in the database (most are), the calculator will use that. Otherwise it will use the default of 1 g/ml (spec grav of water). Others prefer to leave it unchecked and use 1 g/ml, as it tends to be a little more universal. I do the latter, mostly because I also keep my recipes in a spreadsheet and it is easier to put in flavors at 1g/ml.
Water - 1 g/ml
PG - 1.036 g/ml
VG - 1.26 g/ml
Alcohol - 0.787 g/ml
The calculator uses the PG/VG weight for nic base, as the difference is negligible.