I'm sure glad it went well for you! You'll be a professional chicken wrangler in no time at all!
Your bigger ones are still babies. Don't handle them unless you need to. Touching them however, is another matter entirely. If they're terrified of you just go into their coop at night when they're all on the roost and it isn't totally dark yet. They should be able to see you and not willing to leave the perch because it isn't quite light enough. I just go down the perch and touch each one gently and briefly on their backs. I speak softly to them and tell each one goodnight.
I don't do this all the time, just on occasion. I have too many birds and many of them are in pens that I have to struggle to get into so don't do it unless absolutely necessary. I try to teach them that I'm safe but I don't spend an inordinate amount of time doing things like that.
I believe the application of VetRx at 4-5 times per day is direct application. I usually only do it once... in the evening. I dont have time to do it that often. If you have the time, go for it. You might just get some speedy recoveries in the barn... and yes, til they display no more symptoms.
When you pick up your older birds, you just need to hold them correctly so they will relax. Like this...
The chicken's weight is supported by his forearm, the legs of the chicken are between his fingers. He probably has two fingers between the legs with the thumb on the outside of the leg and the pinkie or pinkie and ring finger on the outside of the other leg. Hold them firmly, not tight, unless they struggle. If my birds struggle, I tighten my grip on their legs quite a bit and they seem to understand this. Once they relax, my grip relaxes as well. It's still a firm grip, just no longer a tight grip.
You have a hen that is mean to you? That's fairly odd. I have the occasional hen that seems to have gotten a twisted feather up her hiney but they are very few and far in between. They don't stay cranky for long. If they bite me when I'm in the barn close to the perch, gathering eggs, they find themselves on the floor... it's just a reaction. I usually end up paying the most for it though as I have to bend over and catch them in the almost dark and put them back on the perch.
If you need help with that hen, I have some information I can send you. Why don't you tell me what she does?