1. The course of the surgery is planned according to the results of corneal mapping and the refractive test (objective and subjective). Performing a Custom HOA (Higher Order Aberrations) correcting surgery is not recommended as it may result in removing much more of the corneal epithelium than a surgery using so called ‘preset’ laser.
2. SBK method is not connected with optical sphere (it can be 8,0nm max). It is not recommended to widen the optical sphere in high refractive errors. In comparison with conventional LASIK method, the SBK surgeries are followed by lower degree of ailments connected with the Dry Eye Syndrome.
You can find more details about SBK LASIK method here.
3. Working in front of a computer should not cause a relapse, however, in a case of such severe astigmatism (3,5D and 4,5D), a possibility of regression cannot be ruled out.