The calls come from businesses that want to be taken over in full, not public firms where berkshire takes a 10% stake.
The equity investment made with proceeds from yen denominated bonds, so it doesn't imply a bet on a weaker dollar (the debt would be more expensive to repay if the yen were to strengthen)
Berkshire has made large investments in companies (outside their insurance float capital) where they weren't buying 100% ownership. See their investments in Goldman Sachs, BofA, Pilot Flying J, Nebraska Furniture Mart, and others.
Buffett and Berkshire are attractive as an investor because they send a strong confidence signal and because they are known to be extremely hands off.
The equity investment made with proceeds from yen denominated bonds, so it doesn't imply a bet on a weaker dollar (the debt would be more expensive to repay if the yen were to strengthen)