1) Yes, but note that the pikemen do not have to be deployed in 2 ranks.
2) ReG is irrelevant. The longbowmen can deploy in any rank If by "protection" you mean, do the longbowmen cancel factors as if they were pikemen then the answer is no.
The most common deployment could be two wide and four deep.
PP
PP
LL
LL
The mixed UG could be deployed as four wide and two deep.
PLLP
PLLP
(Note: If an enemy UG only contacted in melee the left-hand file of pike, an MF1 move could move the remaining two pike from the right-hand file and place them behind the left-hand pike, creating a file 4 deep).
Alternatively, it could deploy four wide and one/three deep as
PPPP
LL
LL
This probably isn't very useful.
Richard