John,
Great questions. Flynn did not, in any of his writings, mention any influences, conceptual or otherwise, on his hole designs. To look at the entire body of his work it is easy to recognize the influences of Pine Valley and of Merion. In each case it is not that easy to determine which direction the influence lies if you know what I mean.
Flynn was clearly inspired by some holes, for instance the 7th at Pine Valley as he created a close copy of it at Boca Raton South on the 17th hole and varied more so conceptually at Cherry Hills on coincidentally its 17th.
As for the Redan concept, Flynn seemed to have his own variations which did not resemble the original very closely. Flynn's variations had more of a narrow and steep slope to the green. The ability to play a run-up shot was not encouraged as the openings were normally pretty tight for the distance played. I'd say the Redan-like hole at Huntingdon Valley, the third has a wider opening but a fairly steep slope. In Flynn's variations the object was to land the ball on the green, generally into the bolster on one side and feed the ball to the hole. It is an example of Flynn being a transition architect towards a combination of aerial shot demands and ground and aerial shot options.
Huntingdon Valley #3
The left side of the green was built up by Joe Kirkwood. The green used to fall off the left side so that only well-executed shots would hold the green:
Philadelphia Country Club #7 (my mother-in-law aced this hole twice) Notice the narrow opening and steep upslope:
Philadelphia Country Club #11
It looks like it could play like a Redan but the green does not slope right to left and there is no functional kicker:
And then there is the 7th at Shinnecock Hills. There is some controversy among the treehouse but I am convinced that the records prove that the green is Flynn on the former site of the Macdonald green. This photo shows the approach from the abandoned Flynn tee. Today the hole is played from the former Macdonald tee. The steep upslope does not encourage the ground approach (although there is a wide-enough opening) as does most of the Macdonald/Raynor/Banks versions: