Fine motor comes in on the two visual spatial subtests of the WPPSI-IV. Tasks differ on the SBV, depending on her performance on the routing tasks (vocabulary (verbal knowledge), for the verbal tasks, and matrices (nonverbal fluid reasoning) for the nonverbal). It is possible that a strong performance on the nonverbal routing subtest may put her at a level where hands-on pattern assembly will be a significant part of a subtest score. (Some level will be present,but fine motor demands vary.) No such problem will occur on the verbal section. If using the SBV, make sure the examiner is clear that the referral question is giftedness, as the Early SBV, which can be administered to kids age 2 - 7-3 in the NT and DD population, is not appropriate for gifted.
There are usually 6 subtests administered in the WPPSI-IV, at this age, and ten on the SBV. Having fewer subtests will not necessarily inflate or depress the results. Sometimes having more will lower them, as young children tire quickly (although the subtests usually go by quickly on either test).
Measurement of verbal ability is, as you suspect, associated with environmental enrichment. The visual-spatial tasks are less so--but may be impacted by fine-motor skills, which may be quite different from cognitive development. This is one of the reasons why any cognitive assessment done on three year-olds should be taken as provisional only. If you go into the testing with realistic expectations about the validity and stability of early childhood testing, then it will be valuable, but not quite so stress-inducing. Be prepared to have her re-tested in another four or five years, if you want more stable and accurate assessments. And also, remember that you don't have to make decisions for the next decade of her education right now. If you have to change in a few months or years, it's okay.
