TTL on glue records and PTR records

[chubirka]

I'm a parent zone, gwu.edu, and I've been having a discussion with one of the 
admins of my delegated subdomains, va.gwu.edu, regarding a couple of issues:
1. I thought that my zone TTL only affected the glue records of the delegated 
subdomain, NOT the entire zone. Doesn't the SOA information in the zone file 
of the delegated subdomain set the TTL for all records in the subdomain?
2. He has multiple "A" record names pointing to the same IP addresses for his 
nameservers, but his "PTR" records (of course)only indicate ONE "A" record or 
canonical name. He initially wanted me to use the names which DON'T coordinate 
with the "PTR" records and this was seen as an error by various error checking 
programs, so I reverted to the canonical names which had the coordinating 
"PTR" records. He seems to think this is unimportant, but I prefer to avoid 
this kind of error whenever possible (The entire subnet where the nameservers 
reside is also delegated to this administrator).

Any comments or thoughts?