Alright lets see

1) As to your first question. Alchemy is basically capable of performing nearly any feat, however there are limits. These limits are divided into three casts. A level 3 cast, which is basic form of Alchemy not too strong. Say something like summoning lightning or causing a small kinetic explosion. Than there is a level 2 cast, which is nearly a 100% stronger than a level 3 cast. However using this sort of power requires permission from the higher authorities. Finally there is a level 1 cast. There is very little known about a level one cast, accept that its power can have apocalyptic results. So far in the story level 2 and level 1 casts are not allowed. And we will all start with using level 3 casts.

With that said, body alteration is a fairly easy feat with Alchemy. Hence yes you can give your self claws, blades etc. Than falls under shape-shifting. Also as mentioned in the OOC all Asylums have an Alchemic Speciality, which is the form of Alchemy they are most proficient in using. However this does not mean the Asylums are ristricted to that form of Alchemy, they can use any type of Alchemy they want. Lightning, fire, wind, friction etc. However there are a few limits to this.

2) I don't quite understand your second question. Are you asking if it is objectionable to kill someone using Alchemy? Well yes, that is what A.M.R.O over sees. The only people Asylums are allowed to kill with Alchemy are rogue alchemists and people whom A.M.R.O deems a threat. However in self-defense, the use of Alchemy is also pardonable but Alchemists are not allowed to reveal this art to normal humans,

3) You can engrave sigils into your skin however in the end it will prove futile. The reason for this is, an Asylum can create up to three sigils at a time. The reason being, this style of Alchemy is fairly difficult and takes a higher toll. Also once a sigil is used it fades away, this is the reason why it would be futile to tattoo it on your body.

If you have any more questions, please don't hesitate to ask. =)