Hi Jifnif:
Most of the things you mention are billed by the facility (ie the hospital) not the ER physician.
Even the hospital does not bill oral medication administration. It's included in the facility E/M code. Nursing work involved in injections and infusions are also facility codes only. Blood draws are usually facility charges. The drugs themselves are billed by the facility (J codes). Transfusions are ordered by the physician, not usually personally performed by the physician-so they are facility codes.
Physician billing is mainly E/M levels 99281-99285 plus 99291, 992921 critical care.
Major procedures coded for physician billing would include fracture management, wound repair, I&D, FB removal, joint reduction, joint aspiration, chest tube placement, emergency endotracheal intubation, central line placement etc. Coding for splinting and casting are tricky- modifiers and codes depend on whether the doc is providing complete care for the problem or temporizing until patient can see a specialist.
Wish there was a book just for the ER-maybe Ingenix should write one!
I hung out at a number of discussion boards and took several webinars when I started. The AAPC specialty course for Emegency Department coding should also help.
Good luck!