1. as a personal suggestion, I'd say go with Narkotix. He's very fast, on the customer care team of gunbot and a generally good fellow. but, I'm biased, he sold me my first bot, then my second license ... the last one he made happen in less than one hour on Christmas eve. so, you understand why I can recomend the fellow.
2. no. you keep your private part of the API key. no exit scam possible. at least I don't see how, since you don't need the API key to be able to retrieve money, just fetch data and make sell and buy orders.
3.I'd say yes. if something goes wrong, we're still here to help, there's the telegram group if you use telegram, the wiki is quite comprehensive ... and if everything else fails, you can still get in touch with Nark. but: be aware, the bot is still work in progress. there are updated versions coming in regularly. some fix bugs from previous versions, and eventually they can get new bugs. bugs can be frustrating.