I thing that Evans Gambit is not so useful. Before proving this have a look at the mainlines at the Hungarian Defense:

When Black uses Hungarian Defense, he mostly wins.

Same thing can happen in Evans Gambit also:

Thank you in advance for commenting on my ideas.

Interesting. I've used the Evan's gambit in a few of my games (I'm a fan of both the Italian game and unorthodox openings, so go figure). My opponent has, so far, always been able to equalize, but I may not have been playing aggressively enough.

In simple, transpose the Evans Gambit into Hungarian Defense. Another point, we should be an offensive player to play Evans Gambit or else balck will equalize.

Where to start?

For one thing, a big difference is that it's White to play in the second diagram. This allows him to go for 7.Qb3 Na5 (what else?) 8.Bxf7+ Kf8 9.Qa4 Kxf7 10.Qxa5 -- completely different situation compared to the Hungarian.

Secondly, 5.c3 is hardly the best move in the Hungarian -- 5.dxe5, 5.h3, 5.Nc3, 5.d5  and 5.0-0 are all more popular than 5.c3.

Thirdly, where did you get the idea that Black usually wins in the Hungarian? If that were true, nobody would play 3.Bc4, and everybody would play 3...Be7. In Game Explorer, in the position after 4...d6 White wins 42%, Black only 27%.

In the second diagram it is white to move and in the first black, therefore it is not a transposition. So if black plays that way white gets an extra move and more open lines for his pawn. The black position looks quite solid, but maybe white can just regain his pawn with 7.Qb3, on ...Na5 8.Bxf7+ and then something like 9.Qa4

This.

Hehe, je was net iets eerder Scarblac

yup, 5...Be7 means there's no good way to stop Qb3 and Qxc7+ without giving the pawn back. The best move here is 5...Ba5. This is the move GM Dzindzichashvili suggests as the strongest. It eyes the e1 square( because it is most likely white who will want open the game up), not allowing the white rook to move there, and becoming extremely annoying in the process.