Forward pass doubt

[dvasques]

Once again, here I am. This time I have a doubt about a penalty enforcement.
And, once again, I am sorry that I'm asking all this doubts about NFL rules in this forum. Maybe you guys will shed some High School light on me and I'll be able to change this rule down here in Rio.

NFL Rule 8-1-Penalty c states:

For a forward pass from beyond the line: Loss of down and five yards from the spot of the pass.

Then, on a Suplemental Note it states:
When a distance in Penalty 8-1-c (the above)leaves the ball in advance of the necessary line, it is first-and-10 for the offense.

So... let's say it's 3rd and 1 for A at B45. A9 scrambles and starts running forward. At B35, A9 launches a forward pass that is complete at B30.
So, the pass happened at B35 and that's your point of enforcement. So the ball will be pulled back to B40.
B40 is beyond the necessary line.

So by commiting this foul, team A won't really be penalized because those 5 yards they lost are not going to matter since As got first-and-10 at B40?

And what happened to the loss of down? At the very least, shouldn't it be second-and-10 for A at B40?