Incorrect. During partnership days, Buffett only used leverage in dealing in special situations. What our OP is doing is down right reckless. I don't exactly know WB's turnover back then... but if he used higher turnover when younger and then used less. Maybe you should assume that as he learned more about things he improved his method.
Yes, as I said he used leverage. I prefer not to assume reasons for his lowered turnover. There is no fundamental reason why any amount of leverage is automatically bad. Appropriate level depends on various things, including personal risk tolerance.