Please help, I am cnofused.

My question is, when we are making subjunctive or unreal cases, do we actually have to follow the past tense rule disregard what situation we are in? For example:

a) I wish that I could turn the egg that I am holding in my hand to gold.
(Do we need to follow the past tense rule to use "I was holding in my hand? Sounds strange to me if we use past tense here, but the subjunctive rule states otherwise.)
b) I wish I knew how it feels like to lose one of your brother in war in your arms, so I could get him out of his depression.
("how it feels like"? Not "how it felt like"?)
c) I wish I had what William has; he is a genius, unparallel among us.
("William had"? Sounds strange to me if we use past tense.)
d) I wish I had what they are having now, those food they are having costs a thousand dollars per table.
(They are eating the food, if we use "they were having" then it really sounds weird to me.)
e) I wish I knew how many people are here in this stadium, I almost cannot breathe.
(Should we use "how many people were here"? I have no idea. Grammar rule says use past tense)
f) I wish I were a millionaire so I could buy my mom the car she has always wanted.
(My mom still wants that car now, should we use present tense?)
g) If I were the president of this country, I would first clean up the corruption problem this country has.
(This country still has corruption problem, do we actually need to change to past tense "this country had"?)
h) I wish I had the power to control time and actually stop what everyone is doing.
(For this case, subjunctive tells us to use past tense, which is "what everyone was doing", but if the present tense in sentence a) is valid to present current action, why can't this one?)

I am wondering if those present tense clauses in the examples above should ever be considered as independent clauses, so they are outside the boundary the unreal or subjunctive rule. These sentences do sound strange to me if we use past tense all along disregard what that person is doing or situation is happening. I really wish that EnglishForward' teachers could clarify these problems for me. Is there a rule that states that we can use present tense under some clarifying descriptive condition?