You will have no trouble adding pages to a non-chip PP. I've had it done a number of times. Overseas, some US embassies do it while you wait. Although there is no charge for adding pages, you can pay a $60 expediting fee here in the US and get the pages added in a few hours.
As previously mentioned, the pages are attached with tape-wings.
The 24 added pages run A-X. All are usable for full-page visas except for the first page (A) which has the supplement info and a raised seal.
It sounds like you travel a fair amount, based on your PP page burn rate. You can request two 24-page inserts which will most likely be granted. I used to go for one insert at a time, which was annoying. I once asked what it took to get several inserts at one time. The reply from the consular official: "all you have to do is ask" !
