The enchanted shield, being only 5pts, seems to be broken, considering that the normal shield of an old blood cost 6pt. So by taking the enchanted shield not only do I get an extra AS, I save 1pt, and I also get parry saves because it is stated that it is in fact a shield. Did I miss anything here?
"The enchanted shield, being only 5pts," <--- the part you missed Lizardmen still have to pay the cost listed in our army books.
You also lock yourself out of arguably better magic armors, all of which combine with the regular shield for a +2 or more to your save anyway (well, except for the armor of silvered steel).
How is this? Did the enchanted shield cost 15 pts in 7ed? Does it say in any FAQ that we have to pay the cost listed in the army book? I find this very weird...
To answer your questions in order, the FAQ says so, yes, and yes (in every pre 8th edition armybook FAQ).