Is it legal for PFC to skip SPC and be promoted to CPL without P status (no promotion board experience)?

SGT (Join to see) I have never done this, but from SPC to CPL is a lateral appointment and does not require a board. However, IMHO if you are wearing CPL you should be in a leadership position and acting as a SGT.

It is entirely possible to go from PFC straight to CPL. Really it just depends on the soldier, his or her proven performance, his senior leaders, and if they need an NCO

Yes, it's called being promoted to E4. Both SPC and CPL are E4s.

One is promoted to the rank of Specialist, it can be changed to Corporal, (they are both E-4), Commanding Officer is the Approving Authority (DA Form 4187). While not a hard or fast rule, in Combat Arms MOS's, often only promotable SPC/E4's were laterally promoted to Corporal.
Army Regulation 600–8–19 Enlisted Promotions and Reductions 18 December 2015

http://work.chron.com/soldiers-promoted-corporal-specialist-first-25874.html Hope this helps

Yes

Policies change over time. Back in the day, I was and E-2 with an instant promotion to E-4. The policy then was if you graduated first in your class out of A School, instant E-4. The Catch-22 was the effective date was held in limbo to make sure you could do your 90 days in the scullery underway and then you were pinned and got back pay to the effective date. Trashed a couple sets of dungarees but making E-4 a year and a half early was nice. Still had to do all the E-4/5 technical courses to strike for E-5.

It is you command team only has to do a 4187 to pin that SM CPL but they would have had to put in a promotion to SPC and a 4187 at the same time so they just pinned the SM CPL. If it was from DA then if the SM leaves that unit and still not promoted they would then be a SPC again

Very interesting. I always wanted to promote a Soldier to Corporal but was never authorized one as a company or battalion commander. I look forward to seeing my son attain this grade, as I never got to be one in my early career. I seem to recall, when I was an enlisted Sailor, E3 personnel occasionally being double promoted to E5, on spot, by an O6 Captain.

I can tell you that it is legal. I was one who was promoted to CPL from PFC, however my BN was over strength for CPL at the time. I was a CPL for about a month and then told that i would become a SPC. But since the promotion to CPL was approved at the Department of the Army (DA) level they had to revert me back to CPL. I was also told that if i was to PCS at that time, i would do so as a CPL. The only way i go back to being a SPC is if my chain of command requested that i be reverted back with the final approval coming from DA.