"He would be using something else."
Translation:On używałby czegoś innego.
Ah! When I see 'potzebować' I've been trying to think of it as an older form in English to have need of which helps to remember it takes a genitive. The same would work with 'używać' to make use of. I'll have to keep an eye out for this.
Probably just a typo, but: potrzebować :)
Yes, such a way of thinking about them seems helpful.
On by używał czegoś innego?
I'm really still having quite a hard time with this 'by'-stuff. I think I understand the basics but sometimes it's different all of a sudden.