It's weird to me that this is what's actually used in the game when it would never be written like this (at least not all with katakana) in real life. (I looked it up after seeing your comment because I've only ever played it in English.) If I were forming this sentence on my own, I think I'd say, 「 一人で行くのは危ないです。」 But, I'm not a native Japanese speaker; so who knows? :-)
1) it depends which G you mean. In 'farlig' it is silent; in 'gå' it is pronounced.
2) there are quite a few verbs that are the same in imperative as they are in infinitive. As far as I can see, any which don't end in 'e' (eg: ha, la, dra, gå, gi, si, fly, slå, blø, dø, bidra, snu), but also 'se' ,'le', 'be' etc etc. So 'ta' is one but there are many others.