Your model probably has a lot of polygons, the more polygons you have, the more granular the details of your model will be. We added a polygon optimisation feature, which allows you adjust the number of polygons in your model, which in turn reduces the size of your file.
MeshLab, Netfabb Basic, and Netfabb Cloud Service are free programs that help prepare your 3D files for successful repair upto certain level before going for 3D printing.
Yes, we use check and analyse the mesh for faults. While designs with less need for intervention are not charged, the others carry an extra charge, dependant on the number of errors in your mesh, and the time taken to fix the model ready for printing.