Machine Type: This is pretty standard, if you have a delta printer or circular build plate it will be a delta style build platform. For delta users, you will take your diameter, multiply it by .707 and that will be the X-axis and Y-axis size to input for Build Volume.
Firmware: RepRap(Marlin/Repetier/Sprinter) most printer choices will be for this. Especially since almost every MakerBot/Sailfish style printer I can think of has a build in profile already on the Configuration Assistant you can pick from.
Baud Rate: This is the rate at which USB transmission occurs, your manufacturer can provide this information if you don't have it. **Generally 115200 or 250000** will be the baud rates.
The Build Volume, Nozzle Diameter, filament diameter, number of extruders and check mark for a heated bed are all pretty self explanatory.
Calibrating:
There are a few things you'll want to calibrate for your profile. The default profiles work really well, I think there made to accommodate the Prusa i3's and bulk of the RepRap models. However, there are a few things that you should probably check to ensure great prints.
To access and make these changes, click "Edit Process Settings"
1.Temperature (Temperature Tab)
For PLA the default profiles are 190 C for the extruder and 60 C for the bed. If you were printing with Slic3r or Cura and printing at 215 C for PLA, it's definitely going to have a drastic difference on extrusion if you are now all of a sudden printing with a 25 C difference.
Likewise, for ABS, the default temperatures are 225 for the extruder and 100 for the bed. If your heated bed maxes out at 65C, then definitely be sure to change the setting to accommodate your machine.
2.Retraction (Extruder Tab)
For standard Direct Drive, usually .5 to 2.5 mm will work well. For Bowden style extruders, 5 to 8.5 mm seems to work well. Changing the retraction speed may also help quality, the default 1800 mm/min is usually pretty good though.
3.Extrusion Multiplier (Extruder Tab)
The default extrusion multiplier is .9 for PLA and 1.0 for ABS. If you notice that there's incomplete filling or if there's too much filament I highly advise tinkering with the extrusion multiplier. My general tinkering, I usually adjust the value by .03 at a time for test prints.
Adjusting these three settings can really help setup your printer profile in Simplify3D and produce great prints