Requesting help in tuning a caster

For a campaign, I am creating a character. We are to use the monster advancement rules to become CR 23. My current build is an ancient silver dragon with the riddled and spell-hoarding templates. The concept is a dragon which uses spells instead of force to fight. The general strategy is to avoid direct combat and strike from a range. I anticipate persistent enemies with a strong power base. My overall goal is to survive for three years and become a silver wyrm, at which point ninth level spell-casting will become available to me.

I have mostly completed the build, but am struggling to find good spells for the character. I cast as a level 15 archivist and a level 15 wizard, and am looking for spells to fulfill the following three functions.
1.) Spells to fight off and kill/control an adventuring party of a level up to 23.
1a.) Spells to protect a hidden library from said adventurers.
2.) Spells to subvert, control, and destroy a powerful kingdom.
2a.) Spells to protect a hidden library from said kingdoms.
3.) Spells to obfuscate my presence.
4.) Spells to gain information.
5.) Something better than Craft Golem for a feat...
6.) Spells to weaken and destroy other CR 23 monsters, ranging from angels to vampires to beholder mages to eldritch abominations to melee juggernauts to who-knows-what...

I have 595,125 gold left, a substantial portion of which will be devoted towards the obtaining of scrolls to improve my spell selection. I have access to any Wotc source that is not blatantly unbalanced.

With that information given, I would like to request of the community's aid in creating a viable draconian spell-caster. Thank you.