what are the ALG ports like UDP_ALG_SIP used for in kazoo? They are defined in /etc/kazoo/kamailio/local.cfg

they are there as a simple attempt to have a set of target ports that you can use for signalling that stupid ALGS won't get involved and change signalling IPs and ports.

usually 7000 for UDP TCP and 7001 for TLS ( I Think )

I wouldn't bother screwing around with anything except TLS

You're wasting your time if you don't just set that up right away.

Is it possible to have multiple MWI on one phone, using BLF keys? If so, what do I subscribe to?

nevermind I found it :) Just have to setup a BLF key and subscribe to *97{voicemail box number}. My default MWI subscription prefix is set to *97 (sup kapps_config get callflow dialog_subscribed_mwi_prefix)