In my experience:
1. How long is phase 3 and phase 4 training?
3-ish months each
2. Up to date version of what each phase comprises?
Don't know. They have been known to change. When I did it, Ph 3 (DP 1.1) was almost all recce and Ph 4 (DP 1.2) was command post, Safety, and more recce). But things might be different now.
3. At what point does one do FOO training? What happens after FOO training?
It depends. I'm sure all regiments want their junior officers to get as much gunline experience as possible before moving on to the OPs, but sometimes one doesn't get that chance. Now that deployments have settled down, pers usually have been around for a couple years before the course - but not always as a TC/TL/CPO/GPO. After you do your course, you become a FOO. Regiments were changed last year with the creation of an OP Battery for each and FOO parties are tasked out to gun btys or inf coys when req.
4. What is life like as a new reg force artillery officer fresh off of MOC training?
There may be differences btwn regts, but generally when you're in garrison, it's PT fol by whatever the day holds, whether it be actual training or paperwork. Junior officers act as course officers throughout the year - you may be loaded onto various short courses yourself, given tasks to complete (organize events, conduct investigations, help plan exercises), and manage your troops with the help of your TSM. In the field, depending on your position, you'll be finding gun positions, running the command post, or ensuring the rounds are going to land where the FOO thinks they should. Regiments are getting back into longer regimental exercises now that Afghanistan is basically done, but you'll be lucky if you're out for three months total. That's not a lot, all things considered.
5. What is the dynamic between new officers in the unit and the Capts and more senior officers?
The dynamic is whatever you wish it to be based on your ability to not be an idiot. For the most part, all officers captain and below work on a first-name basis (although some may wish that not to be the case). If you're the new guy, just remember that, for the first while, everyone knows more than you. You can learn something from everyone (even if it's to ensure you don't pattern yourself after them).