Contingency of god in classical theism

According to classical theism god is ontologically simple. This divine simplicity implies that  attributes which created things might interpret as distinct are in reality equivalent within god; that is god's intellect is god's goodness is god's will is god's essence etc. This gives rise to several difficulties but I'll just speak of one in this post. If god's will is in fact the same as god's essence, and god's will is free, then this would seem to imply that god is contingent. To see this just imagine another world, one that is exactly like ours only with one more electron in it. Since in that world god would've willed something different than in ours, and since god's will is equivalent to his essence, then the god who willed to create that world would have a different essence than the god who willed this world. Since his essence differs across worlds, different gods exist in different worlds, and thus his existence cannot be necessary. Aquinas attempts to answer this by making a distinction between absolute necessity and suppositional necessity; if his argument succeeds it would at most prove that there is no contradiction between god's will being free and god's essence being necessary, however it fails to answer the question as to how the gods of these different created worlds can all be one and the same.

Virtual Particles

I must admit that i've always been confused by virtual particles. Are virtual particles "real"? Is the notion of virtual particles scientific? I am most certainly way off here but here are some questions I have:

1. What foundation is there for speaking about virtual particles? That is, in quantum field theory/second quantization states are equipped with creation/annihilation operators, however these creation/annihilation operators don't exist in relation to the internal lines of  feynman diagrams, so what is the underlying formalism ?

2. In what sense can the intermediate terms of a series be said to be "real"? One needs to renormalize just to get an actual physical quantity to be measured at which point the terms corresponding to these supposed "virtual particles" no longer exist, no?

3. According to this thread non-perturbative approaches to qft such as lattice gauge theory don't give rise to virtual particles. Why do physicists say that these virtual particles have an independent existence if they can only be spoken about if one is using a perturbative approach to calculating scattering?

4. If virtual particles can come into existence due to the uncertainty principle(leaving aside the question as to whether time can be introduced as an operator in quantum mechanics and the fact that there is a ground state) then they are by definition not observable/measurable, in which case how can descriptions of  them be scientific?

I have a few other questions about virtual particles but these are the ones i'm having the most difficulty understanding.