Plugs and wires till 100k lol, unless you want to upgrade.
Seafoam no, do that later along with your 100k tuneup.
If you do a trans flush, I'd drop the pan. Clean out the magnet and the pan, and replace the trans filter. Might as well if you are changing out the fluid.
Personally on Auto's I'd do that till at least 40-50k, but if you want at 30k it won't hurt.
Check you brake fluid and power steering fluid condition. You can flush those out too if they look dark, you may be ok though on your 06.