You raise some points I've covered elsewhere. Here is some additional reading:

In regards to prices: https://medium.com/basic-income/wouldnt-unconditional-basic-income-just-cause-massive-inflation-fe71d69f15e7

In regards to drug use: https://steemit.com/basicincome/@scottsantens/the-question-of-universal-basic-income-and-drug-abuse

Here too is my FAQ which covers many many more frequently raised points: https://steemit.com/basicincome/@scottsantens/a-guide-to-basic-income-frequently-asked-questions-about-ubi

Cheers!