New ejabberd user looking for some help

I'm in the process of switching over from jabberd2+mu-conference, both of which seem to be dying from neglect, to ejabberd. However, I'm running into a few problems.

First, what's done and working: I've gotten ejabberd installed and configured on Gentoo Linux, I've registered all of the users from jabberd2, I can bring up jabberd2 in place of ejabberd and users can log in and talk to each other. The SSL cert is properly configured and accepted.

What's NOT working:
— ejabberd won't use the MySQL backend DB I set up, even though I configured it to do so
— I can create and configure multi-user rooms, but nobody can join them
— If I run ejabberd in the foreground, I can see federation attempts to other known XMPP servers being attempted, but they're not succeeding.

For now, the first two are the important ones.

My SQL configuration:
auth_method: sql
sql_type: mysql
sql_server: "localhost"
sql_database: "ejabberd"
sql_username: "ejabberd"
sql_password: "xxxxxxxxxxxxxx"

User ejabberd is granted SELECT, INSERT, UPDATE, DELETE, CREATE TEMPORARY TABLES on ejabberd.*

Here's a sample room's properties:

minbar:root:~:16 # ejabberdctl get_room_options caer chat.caerllewys.net
title
description
allow_change_subj true
allow_query_users true
allow_private_messages true
allow_private_messages_from_visitors anyone
allow_visitor_status true
allow_visitor_nickchange true
public true
public_list true
persistent false
moderated true
captcha_protected false
members_by_default true
members_only false
allow_user_invites true
allow_subscription true
password_protected true
password xxxxxxxxxxxx
anonymous false
presence_broadcast [moderator,participant,visitor]
allow_voice_requests true
voice_request_min_interval 1800
max_users 200
logging false
vcard
captcha_whitelist {0,nil}
mam false

Here's what it looks like starting up:

minbar:root:/etc/jabber:25 # ejabberdctl foreground
kernel-poll not supported; "K" parameter ignored
15:37:59.656 [info] Application lager started on node ejabberd@localhost
15:37:59.658 [info] Application crypto started on node ejabberd@localhost
15:37:59.669 [info] Application sasl started on node ejabberd@localhost
15:37:59.680 [info] Application asn1 started on node ejabberd@localhost
15:37:59.680 [info] Application public_key started on node ejabberd@localhost
15:37:59.694 [info] Application ssl started on node ejabberd@localhost
15:37:59.705 [info] Application fast_yaml started on node ejabberd@localhost
15:37:59.722 [info] Application fast_tls started on node ejabberd@localhost
15:37:59.739 [info] Application fast_xml started on node ejabberd@localhost
15:37:59.746 [info] Application p1_utils started on node ejabberd@localhost
15:37:59.751 [info] Application stringprep started on node ejabberd@localhost
15:37:59.752 [info] Application xmpp started on node ejabberd@localhost
15:37:59.766 [info] Application cache_tab started on node ejabberd@localhost
15:37:59.910 [info] Application mnesia started on node ejabberd@localhost
15:38:00.314 [info] FQDN used to check DIGEST-MD5 SASL authentication: minbar.babcom.com
15:38:00.932 [info] Application p1_mysql started on node ejabberd@localhost
15:38:00.992 [info] Application inets started on node ejabberd@localhost
15:38:00.994 [warning] module 'mod_mam' is recommended for module 'mod_muc' but is not found in the config
15:38:01.055 [info] Application iconv started on node ejabberd@localhost
15:38:01.055 [warning] module 'mod_mam' is recommended for module 'mod_muc' but is not found in the config
15:38:01.115 [info] ejabberd 17.04 is started in the node ejabberd@localhost in 1.75s
15:38:01.115 [info] Start accepting TCP connections at [::]:5222 for ejabberd_c2s
15:38:01.115 [info] Start accepting TCP connections at [::]:5269 for ejabberd_s2s_in
15:38:01.116 [info] Application ejabberd started on node ejabberd@localhost
15:38:01.116 [info] Start accepting TCP connections at [::]:5280 for ejabberd_http
15:38:09.609 [info] (<0.653.0>) Accepted connection ::ffff:99.90.202.211:50025 -> ::ffff:10.24.32.15:5222
15:38:10.642 [info] (tls|<0.653.0>) Accepted c2s DIGEST-MD5 authentication for riteturn@jabber.caerllewys.net by mnesia backend from ::ffff:99.90.202.211
15:38:10.820 [info] (tls|<0.653.0>) Opened c2s session for riteturn@jabber.caerllewys.net/mine

What does it seem likely I'm doing wrong? There's clearly something (several things, in fact) that I don't yet understand about ejabberd.