Anyone on here actually deploy with ANGLICO as a FAC and can share some of the details about their experience? Daily rhythm, movements outside the wire, leading Marines opportunities, unit attachments/ cohesion with such a small unit, ABC training, etc.
OK, it's been long enough that I feel ok about taking a stab at this. For what it's worth, I'm a reservist and I haven't MOB'd with ANGLICO, but I think I can give a decent answer.
ANGLICO will often deploy/MOB as a SALT, which tends to be super-stacked with JTACs. The team commander, each FCT leader, a few of the SNCOs, and maybe the NGLO will be JTACS. While there are efforts to deploy an element that has worked together for a while, in reality you train by spreading out your talent, but when MOB-ing guys you sort of cherry pick the best out there. I'm a Navy dude, but ANGLICO is paranoid about not looking like D-bags out there--the currency requirements on JTACs are so strict that anyone qualified will be fine, but they'll also want to make sure that they don't send anyone forward who can't PT, will shoot himself, or is a jerk that nobody will get along with. There's no need to be an Olympic athlete or circus-level trick shot--I think in general it's "let's make sure these guys are EXCELLENT JTACs and won't embarrass us on the rest." The SALT will go through pre-deployment workups, where the unit cohesion really starts to gel.
Once in theater (or attached to somebody on annual training, which is my primary frame of reference), it takes some time to convince the supported command that ANGLICO will add value. I don't blame them, as it's kind of like if a bunch of dudes showed up your house and said "we can cook, clean, and lower your energy bill, but you'll have to feed us and give us two bedrooms." Their response is often "we were getting along fine without you, so..." Luckily, JTACs are in very high demand, so fairly soon it becomes apparent that you can have an infantry platoon hump six kilometers and then assault a defended position, tired and grumpy, armed with rifles and a few heavy weapons, or you can have ANGLICO bring in US airpower and ISR to knock almost-everything out, then walk in the infantry and hoist the flag.
As far as "inside/outside" the wire, like all things, it depends... I've sort of come to realize that there's a lot of value to somebody sitting there in a cramped tent asking every friendly for positions reports all the time, making sure that our aircraft don't bomb our guys by mistake. It's not as cool, but definitely needed. Once somebody is able to really take care of the overall picture though, it's great to have guys in the field with the grunts.
In my limited experience (ATs, and hearing war stories of guys who MOB'd), it's also pretty common to send folks with the operational units. In this case, you really need to make sure each person adds value, because resupply of water, food, and ammunition can be tough when you're constantly forward deployed. When embedded with a foreign unit on AT, I know I personally had to ask myself "have I helped them enough to ask for half canteen of water?" So to answer that question, when embedded with another unit, my experience is that you JTAC when needed, but you also stand radio watch, or otherwise help with anything that you can possibly can. For me, especially as a Navy dude, it was really stressful to make sure I was adding value to the supported unit in every moment, but each experience was still really rewarding. I got close to each FCT I worked with, as well as the supported foreign or US unit. As far as leadership, you definitely lead your FCT or SALT, and the enlisted soldiers you support certainly look up to you as an American officer and expect you to act as such. ANGLICO is meritocracy, so if you perform, you'll be rewarded with responsibility.
As a JTAC in the field (I'm not sure if it's just ANGLICO, but I never hear "FAC", just "JTAC", even if the guy's an aviator), it's a lot of work with little sleep, and lots of hiking. That's my general view of the "daily rhythm."
ABC training: The reserves (at least my unit) don't do it, although we will do an "ANGLICO challenge" which includes hiking from station to station for graded events about once a year. It's great, and designed to show the individual and the command where you're weakest and strongest. As a dirty reservist, a Navy dude, and a guy who's never MOB'd with ANGLICO, I think you need to be a S-hot JTAC, "pretty good" at PT and marksmanship, and able to be "not a liability" as far as infantry goes. Not sure if it's relevant, but (again, Navy dude) my only criticism of the Marines is that there's a tendency to think "the guy shot EXPERT and got a 300 PFT, ipso facto, he's a great leader!" That's not always the case...
I'll also say that my about 1o-yo son basically thinks that the ideal career path is to be a Marine fighter pilot, then do a FAC-tour where he'll get to play infantry for a bit (and marry a dentist--I swear, that's part of his plan!), as you get to to it all. Then he can do whatever, confident that his "I love me" wall is full of plaques and such.