Welcome!
It is unclear to me whether your reference to +3.0, surrounded by both the terms "standard deviation" and "standard error measurement" means. If it is a z score (which "standard deviation" would suggest), then the approximate FSIQ would be around 145 or so. If it is a reference to the SEM of the FSIQ (which "standard error" would suggest), then it tells us nothing in particular about the FSIQ, though we can infer that it is at least 130 from the Very Superior classification.
I assume that she was actually age 3-11 at the time of assessment, and not quite 48 months, as she was clearly administered the lower preschool level of the WPPSI-IV. Whether she was actually 47 or 48 months at the time of assessment, keep in mind that she is very young for stable scores.
So, to answer your specific questions:
1. at least 130, but possibly up to the 145 range.
2. No, she is not really poor at remembering--or anything else assessed here. Her score is the high end of average, which cannot really be construed as really poor. It is, of course, relatively weaker than her extremely strong visual spatial skills, but hardly an absolute weakness. There are many reasons a score may be low, especially one in an area such as working memory, and especially in a very young child. She may not have been perfectly attentive (which is not particularly unusual in a very young child). She may not have found the task entirely engaging (also not unusual in three year-olds). There may have been other factors (fatigue, hunger, distraction, lack of familiarity with the task-type, etc.) I hesitate to make any type of serious interpretation regarding a lower score on a memory task in a small child.
3. The WPPSI-IV is a cognitive instrument, which is the more appropriate test for classifying an individual as intellectually gifted. The WJ-IV is an achievement test, which indicates the level of academic skill a person has acquired/can demonstrate. One would not use the WJIV Achievement as a stand-alone instrument to determine giftedness. In the case of your child, again, she is very young, and may not have been exposed to or developed certain early academic skills--which is not that unusual for very young students who are later found to be GT. Some GT learners are very early readers, and others are not. The range of expected development for a certain level of cognition is very, very wide at this age. And of course, as with cognitive testing, achievement testing is vulnerable to the vagaries of very small child test-taking skills.
I should also point out that her mathematics skills are assessed in a range consistent with her overall ability, and with her visual-spatial skills. Her word-level reading skills, on the other hand, are very similar to her receptive vocabulary, suggesting that the profile of her achievement is consistent with the profile of her cognition. I would ask additionally if, by any chance, she is growing up in a multilingual environment, or if English is not her primary or first language, as that might be expected to have some effect on the specific subtests I mentioned (receptive vocabulary and letter-word ID). Typically, dual (or more) language learners, have some early lags in vocabulary, but then generally have better long-term metalinguistic (high-level language thinking) outcomes.
