Goal: Learn LaTeX2e completely.
I tried the TeXBook (or rather, got some of my team to try reading it). It's got a lot of obsoleted/removed references (\tenrm, for eg).
Or should I start with LateX Companion?
Do the LaTeX2e books omit concepts already covered (and still in use) by TeXBook? (That is, does reading just the LaTeX2e books let me learn all of LaTeX2e, including the parts that are inherited from TeX?)
Related to this question.
\tenrmis not obsolete at all; it's just not defined in LaTeX but in theplainformat for TeX. See e.g. What is the difference between TeX and LaTeX? for more information on the difference between TeX and LaTeX. – Alan Munn May 02 '18 at 03:39tex-coreis for core TeX stuff and not a suitable tag for a question about LaTeX (of any variety) or its relationship to TeX. I've used thelearningtag instead, but I'm not sure that's the best choice. – cfr May 02 '18 at 03:56learningtag. – May 03 '18 at 07:16