This article is a must read.
1) The Netziv on our parsha asks a question that I don’t completely understand. The builders of the mishkan were, “Kol ish chacham lev asher nasan Hashem chochma b’libo…,” (36:2) wise people that Hashem granted wisdom to and inspired. Netziv asks: how could Hashem grant “chochma b’libo” to certain people so that they could participate in building the Mishkan? “Hakol b’ydei shamayim chutz m’yiras shamayim” – Hashem can give a person a lot of things, but he cannot give a person yiras shamayim. That has to come through free choice. Now, I think I’m being charitable to the Netziv by using the word “inspire” for chochma, but in reality, I think the word I should have used is brains. That’s why I don’t quite get the question. G-d does not distribute smarts equally. Some people have it, some people don’t. G-d gives each of us different talents to use to the best of our ability, whether it’s the ability to build a mishkan or the ability to play violin, or the ability to think. What does that have to do with yiras shamayim?
Be that as it may, his answer is a great point. Netziv quotes the continuation of the pasuk: “…kol asher nisa’o libo l’karvah el ha’melacha.” The people who were given the talent to build were those who chose to step forward and wanted to help. Anyone could have stepped forward – but not everyone did. Those who did were rewarded with ability commensurate with their desire.
2) “K’chu mei’itchem terumah la’Hashem kol nediv libo y’vi’eha es terumas Hashem…” (35:5) Seforno comments on the switch from "terumah la’Hashem” to“terumas Hashem” and explains that the pasuk is referring to two different gifts. The “terumah la’Hashem” was the voluntary donation; “terumas Hashem” was the required half shekel each individual had to bring.
Chasam Sofer answers that everything that we own is “terumas Hashem,” Hashem’s money -- if he didn’t give it to us, we wouldn’t have it in the first place. Any donation we give is like drawing a check against someone else’s account and then presenting it to them as a gift. So why not just cut out the middle man, i.e. us? The answer is that Hashem wants us to exercise our generosity; the money he gives us allows us the means to do so. Our job is to turn the “terumas Hashem” into “terumah la’Hashem,” a gift to G-d.
The Sefas Emes brings out the same point using a different diyuk. Why does the pasuk, “Kol nediv libo y’vi’eha eis terumas Hashem…” adds the word “y’vi’eha” when it could just as easily have said, “yavi eis terumas Hashem?” Sefas Emes answers that “y’vi’eha” is not talking about the terumah, the physical gold and silver that was brought, but rather is referring back to the previous clause, the nedivus lev, the spirit of generosity, of “kol nediv libo.” That’s what Hashem really wants from us. That’s the “chutz m’yiras Shamayim” that has to come from us.
3) For something on P' Shekalim, see here from my wife.