1. You are either in an MBZ or a CTAF, you can't be in both at the same time. If your ALA is contained within an MBZ then you make the same taxi calls on the MBZ as you would if you were departing the primary field the MBZ is associated with, although you'd include your ALA departure field so as not to confuse any traffic).
From
Jeppesen ATC Departure, Approach and Landing Procedures page 718 para 6.3.3:
Taxiing reports and broadcasts must include the following information:
a. aircraft type;
b. POB (taxiing report for IFR flights other than RPT);
C. IFR (if operating IFR);
d. location;
e. destination or departure quadrant or intentions; and
f. runway to be used
In your MBZ scenario you are making a broadcast rather than a report as it is to MBZ traffic not ATC. Therefor you can omit the POB.
2.
Jeppesen ATC Departure, Approach and Landing Procedures page 717 para 6.1.1 describes what to do in this situation. Basically you don't have trouble with traffic as you can make a broadcast on the MBZ and Area VHF (just because Centre can't hear you doesn't mean that relevant traffic can't hear you). However you do have a problem with maintaining a sarwatch.
You can go if you establish comms with ATS as soon as possible after take-off and no latter than the MBZ or CTAF boundary. If RPT, CHTR or AWK you must have radio contact with your operator who must have immediate access to a phone.
Also, if not RPT you must establish a sartime for departure.
I guess in practical terms, if you weren't anticipating comms problems, you'd have to call your base on the radio, get them to ring ATS and establish a sartime. Then you can go.
Now we'll wait for someone to come in and tell us what obscure exceptions exist
