Displaying Silver Points in the menu is relatively easy, but the hack work required to get there is trickier.
Weapon/armor effects: Data for these start at 0x0C2A05, and each one is three bytes. The first byte determines what effect it has. In the case of 33% damage, the data would start with 02. The next two bytes will be something like 02 and 06. Looks like it's 02 01 03. 1 * byte2 / byte3 = damage modifier. If byte3 is zero, the value is not divided. If you change the first byte to 0B, it will become a magical attack with the same modifier.
You can't easily apply an element this way, but I could make a hack that would allow for that.
Palette plugin: You'll need, as a bare minimum, the data size, start location, if it's compressed, if it stays in the same place when modified.
In this case, it will stay in the same place, and all data is sequential. When configuring your SaveRecords, create a new array at the size of the total number of records. It can stay in the same place, so bOverride should be true. nOrigSize, nDataSize, and nMaxSize should all be 0xD2. I don't think these are compressed, in which case bCompressed will be false.
The original address is the trickiest part. You'll use GlobalShared's GetRomAddr() to find the base, then add set number * 0xd2, and a couple other functions thrown in to organize the data. This part is the most annoying.
I was going to finish this explanation with a couple more paragraphs, but I'm now halfway through a new plugin.