The DCT one is. But usually the whole is too small, anyway

(vaping is full of "that's what she said")
Get the self-tapping valve. There are some dedicated carto punches around, but they are sorely overpriced.
I honestly don't know what to say about the battery types... IMR (lithium manganese) are considered "safer chemistry" because in case of catastrophic failure the resulting stuff doesn't ignite or explode. The regular chemistry ones (cobalt oxide, I believe?) go boom if they short. These ones can be either "protected" (i.e. they have an overcurrent protection circuit that cuts off the battery if it discharges too fast) or unprotected (a big no-go for vaping purposes, see the exploding e-cig stories). The story further goes that the protected batteries are just as risky as the unprotected ones because (1) you can never be sure your battery isn't, in fact, a knock-off that's not really protected or (2) the protection circuit fails silently, i.e. you only know it had failed at some point when the battery explodes...
Someone with more experience should comment on whether the E-Power's switch would protect you against an atomizer short. I believe it would, and fail permanently as a result, but I'm not sure.
The only other danger is if the battery shorts due to a defect so be wary of using a battery that suffered any kind of hard knocking around, and check the integrity of the wrapping around the battery every time you put it in. Also, don't charge batteries overnight, unsupervised.
I don't know what else to say...
ETA: ECF officials claim that all the horror stories with exploding batteries happened with PVs that had two batteries stacked. We have no way to know for sure if this is the case.
The other issue is that batteries explode / burn up on charger all the time, but not when in use. The point is all batteries have this risk - sealed / proprietary e-cigarettes, cell phones, camera batteries, RC toys etc. No going around this one.