not quite: its about accumulating capital yes, but also with private ownership (as opposed to collective ownership) and the use of said capital to gain more capital (investment returns put back into more investment)
> renting stuff is more profitable than selling stuff
maybe, maybe not, but it is usually more stable and predictable
Nope, you can have capitalism where the vast majority of the population is legally or economically barred from owning anything. The only private ownership required in capitalism is that of the means of production, which says absolutely nothing about the rest.