Excellent advice given by Newbee.
On the bass issue, with a dipole close proximity to the rear wall or a corner can actually decrease rather than increase the bass, because it's the out-of-phase backwave that's getting the benefit of boundary reinforcement.
In general, reflections arriving before 10 milliseconds tend to be detrimental (can induce coloration and/or screw up the imaging), while reflections arriving after 10 milliseconds tend to be beneficial (convey a sense of ambience and spaciousness). Just for the record, this is an oversimplification. Anyway by placing his speakers 4.5 feet out from the wall, Newbee is introducing a roughly 9 millisecond delay of the backwave energy. So when it arrives, it is late enough to be more beneficial than detrimental. By also diffusing it, he minimizes any residual detriment to the imaging while preserving enough broad-spectrum late-arrival energy to give a good sense of liveliness and rich ambience.
By toeing in his speakers strongly, Newbee is directing the frontwave energy in such a way as to reduce the magnitude of the early sidewall reflection. A bit of diffusion in the early sidewall reflection zone areas would be helpful with a fairly wide pattern dipole (Maggies or SoundLabs), but with Quads or InnerSounds or Martin Logans the radiation pattern is narrow enough that the toe-in alone should be sufficient.
Dipoles are often quite happy up close to the side walls, as their figure-8 radiation pattern has a null to the side. Placing the speakers up close to the side wall is often the only way to get sufficient center-to-center distance to give you a nice, wide soundstage. So once agin Newbee is right on the money.
Methinks the moniker "newbee" was chosen to sucker us into letting our guard down. This guy ain't no newbee.
Getting back to Glai's questions, 2.7 feet out will impose roughly 5 milliseconds arrival time delay on the backwave, which is definitely helpful. I'd recommend lots of diffusion, just like Newbee said.
I don't think that jamming a metal object through the grill would be a good experience for your son. He'd probably get a painful (several thousand volts) but low amperage shock.
I had three kids and unprotected ribbon speakers in my living room, and all it would have taken was a finger-poke to ruin the ribbon. I told the kids that those were daddy's toys - don't touch. My kids never did. I made a grille to protect the speakers when the neighbor kids came over, but alas it wasn't enough. I came home one day to multiple finger-sized holes in one ribbon after the neighbor kids had been over.
You might want to have some canvas or bathtowel-materal speaker covers made to protect the speakers when you're not playing them.