I agree with the first for practical reasons. Self defence is sometimes necessary and escape not always a practical or the safest option, so I don't see the problem with legalising things that can be used very effectively defensively but have little to no scope to cause any permanent harm in the hands of someone who might misuse them. No point legalising guns, in that case - self defence is the only legit argument for owning a handgun, and once that can be equally achieved through non (or, more accurately for tasers and such, less) lethal weapons there ceases to be any reason to own something designed to kill people.
I strongly disagree with the castle doctrine. It's hard for me to get across just how strongly. Lethal force should always be an absolute last resort only to be used to prevent an imminent, serious threat to your and others lives. I do acknowledge that there's a debate to be had over whether you should be required to attempt retreat or not inside your own home (essentially whether your right to defend your own home trumps your requirement to make every effort to avoid seriously injuring or killing someone in cases where the outcome is pretty much the same with regards to your personal safety). If that debate comes down on the side of defending your own home, then yes, there will be more cases of legitimate use of deadly force in defence of your own life in your home than there will be out of it. But giving people a carte blanche to murder anyone who crosses their threshold? Certainly not.