Ah, another de Soleil!
Stay With Me is an excellent emergency skill for Physick.
Bear in mind that there will be two battles each event. One you can play in, one you should monster in (itâs great, you get to run around being an orc barbarian while your character is perfectly safe. You can even be an orc physic if you need the practise).
You may get dragged out on battles and quests anyway. The healers are usually WELL looked after. 
Iâd go with the herb garden. Youâll be able to sell a few, swap some with apothecaries, and not rely on finding someone else. OTOH, you may want some cash for other things⌠In your house, I suspect that youâll have a good support network.
Charging⌠yes⌠As you say, in the battle, you generally donât charge. The closest Iâve seen is a Leaguer physick who used to tuck his business card into folks bandages. âIf you have enjoyed our saving your life, why not drop by the X and thank us in person? All donations gratefully recievedâŚâ
In the hospital, well, they generally get donations from various people.
If on skirmish, youâll likely be with your fellow Dawnish if not de Soleil. You arenât going to let your brothers die because they wonât cough up the cash are you?
Other than that⌠fixing folk after a tournement (uncommon)? Patching people up after a duel in the street (rare)? A couple of rings, maybe?
Healing at Anvil is not really done to make money. Itâs done to make friends, and a reputation. Think of it like this. Your character may go home after the event known as the guy who healed the Earl, the Senator, that Battlemage, from all manner of contusions. As the reason half of de Soleil is still breathing. You canât buy that.
Quite often, the healer doesnât NEED much money. Theyâll get assigned a bodyguard knight, passed all the herbs looted in downtime, and checked in on regularly. âMy lord, I require funds to ensure our knights survive this day?â âSeneschal, give Tristan whatever he needs!â
There are some places that will sell you little sets of surgery tools at the event. Chows emporium, for startersâŚ
As for songs, Iâm sure youâve found the Dawnish music wiki⌠The classics are of course Brittaâs Glory and the Imperial Battle Anthem.