As far as B. is concerned, in my experience you can actually softlink the newer libical to the library name that the compiled PBSPro expects and it should work – it’s only libical2 that (very slightly) breaks the ABI/API.
[By the way, if you want to specify reservations with timezones that use daylight saving time it’s worth recompiling with the beta libical2 library after some trivial tweaks – there are some small bugs with DST switching in libical1 that can make your standing reservations start an hour early/late for a week or so when the DST changes. Of course if you value your sanity you’d actually use standing reservations that use a timezone that doesn’t jump around, e.g. UTC.]
I consider that missing .0 DSO a CentOS bug, BTW, since 7.1 is supposed to be backward compatible with binaries compiled for CentOS 7.
Normally when you change only the minor release number in a distribution you keep the older DSOs around for your packages when a new version comes out, to retain backward compatibility (that’s the whole point of naming the new library .1, so it can coexist with its older sibling). Of course on some distros that sometimes requires you to install some “compat” RPMs, and perhaps no one bothered to build one for this package.