Never tried Kratom, but just got some sumatra and green malay and I have some questions...

The person at the store said that the sumatra was like an herbal adderall, and the green malay was like 50/50 opiate and speed. If I do the green malay tonight, is it safe to do the sumatra tomorrow? What kinds of effects would I expect from the malay, and how long does it last? Could I do any kind of creative work while on the malay? Should I stay away from weed while on kratom? As a first timer, if I do these two days in a row, will I feel terrible without it afterwards?

Thanks!