It's hard when you're new because you have all kinds of different advice coming from all different directions. Until you get some experience, and though trial and error, you'll just have to gather all that information and come up with your own way of raising your animals. You'll learn over time what works best for you.
Yes I know what really works for me. When my chickens have worms, or I need to treat preventativley, then I use a wormer, When I suspect my chickens have coccidia, or are I treat preventatively, I get a coccidia treatment. I go to my local co-op,
TSC or feed store and just pick them up and use them as directed.
I have never used garlic or pumkin seeds. I have heard of people using garlic and cayenne, and some use Molly's Herbals. I don't use these, and I never have any problems. I've never heard of pumkin seeds, maybe someone can post about the rational regarding using pumkin seeds.
though I can tell you right now, if you're eating the eggs of these chickens remember that you get out what you put in. Garlic and onions impart a taste on the eggs. Cayenne does not. You need to read the label on the wormers and coccidia medications to see if there is a waiting period before consuming eggs or meat from chickens treated. I don't know. I haven't had to use any wormer or coccidia treatment in quite some time.
Your chickens most certainly will not die if you don't use a medicated feed. I've never used medicated feed and mine aren't dying. I make sure they have been vaccinated against Merek's, I give them a good layer mash and access to *clean* and fresh water at all times. The ones who don't free range are provided oyster shells and grit free choice. I don't use garlic or pumkin seeds. Scratch is a treat, not a meal, for my chickens.
If I were you, I'd get a book on how to raise chickens. Storey's has a good one that I like quite a bit. I refer to it a lot.
Maybe others can post what they do, and you can make your own choices based on all the informatioh you have at your disposal
And remember, if theyr'e healthy and happy, whatever you're doing, you're doing correctly.