Your question requires a two-part answer.
\sc
and \bf
(and \it
) are deprecated because, as you have noticed, they override each other. Use either
\textit{...}
\textbf{...}
\textsc{...}
or
{\itshape ...}
{\bfseries ...}
{\scshape ...}
instead.
However, not all fonts contain italic and/or bold small caps (when they even contain small caps).
(Also, italic and small caps usually don't combine at all by default, requiring \usepackage{slantsc}
to do so.)
When you load the T1
font encoding, you're replacing the default Computer Modern fonts by CM-Super, a larger but lower-quality set of fonts that look mostly identical but contain many more glyphs. In older TeX distributions, you might even end up with bitmap fonts in your output.
The Latin Modern fonts are a better alternative (\usepackage{lmodern}
), but they unfortunately don't contain bold small caps.