Following my insights on general tactics for Word Bearers, there are some things I didn't cover but I will cover them here.
Word Bearers must take a second compulsory HQ choice who must either be an un-upgraded captain (no consul choice) or a consul Chaplin. This can make Word Bearers hard to run at lower point games: with 10man squads as minimum you cannot add characters to rhino units, as such you will need to buy them special units or forgo rhino transports.
Any WB character (including sergeants) can take tainted blade. Never take these. Full stop, just don't. Instant death on 6s ap- Str: user for 10 POINTS ARE YOU CRAZY, NEVER TAKE THESE. Just buy power swords, deny challenges and cut through normal marines.
WB also gain access to a special type of Consul: Diabolists. These guys have the demon rule (5++ so no need for refractor field). These guys give you access to the Dark Channeling table which is nice but is expensive. Also they can't take bikes or jetbikes.
Our characters are neat because they count as Diabolists and Masters of the legion so we don't need 3 HQ to take our formation. Erebus is also a Chaplin and the two above so is super (but you still need one more HQ). They most give you access to Demon allies without taking the rite of war/formation (which is nice but you should be investing in your marines until you get over 2000 pts). Most unique characters are also psykers. Erebus has ML1 Biomancy and telepathy, as does Kor Phaeron. Zardu Laylak is Mastery Level 2 and can take powers from Pyro or maelefic (which he can use without fear of perils because of Demon).
Zardu give nearby Word Bearers (12") +1 to combat resolution, and once per game may reroll to cast a power. He is possibly the best choice as of now (will be the compulsory HQ, followed by the extra HQ) as he is cheaper than Erebus and gives out a nice buff bubble. Finally he gives you +1 on your roll on Dark Channeling which means you are more likely to get Demon (not super but nice, hatred or +1 Str is better).
Kor Phaeron is not so good but fluffy. Don't take him unless you want to do a campaign or something.
EDIT: I will be doing a focus blog post on Hol Beloth.
Word Bearer HQ are for supporting your army not for going face to face with other chapters beat stick HQ CQC monsters.
Next post will be synergy, units to take/not to take and combos.