1. any headstamp case will work. yes people will the brass is different thickness, that is true. People will say that you need to reduce your loads by 10% when using Lake City or other military brass, if you don't there is no such thing as the reloading police. Ive loaded over 10,000 rds of 223/5.56 for both AR platform and single shot rifle, my powder charges stay the same for military or commercial brass, meaning i do not reduce because of military brass.
2. you may use any company primer you wish. Just make sure you get the right ones. all the boxes for 1 company look the same. for 223/5.56 your looking for Small Rifle Primers
3. yes any 55gr bullet will work with the load data. There will be other data for Cast bullets, but your only using Jacketed bullets so you will be fine.
Always write your recipes down, it makes it easier to reload from a piece of paper rather than a few manuals out on the table. I have everything on my Android phone, as well as a database here on my netbook of all my recipes for the 17 calibers i reload for. And i keep getting new calibers when i buy new toys, or my buddies do and they want their data saved.
If some give you data, take it with a gain of salt. Always refer to your manuals before you take reload someone elses recipe. yes it may have worked for them, or they are having a bad day and they told you to charge your 223 case with 30grs of powder rather than 24grs. That would probably make for a bad weekend, for both you and the gun.
Take it slow at first, only have 1 powder on the reloading bench at a time, only have the brass you want to reload out on the bench. Only have the bullets you want to reload out on the bench. Meaning, keep your reloading bench clean, super clean. Ive seen so many people on forums that charged 100 cases with the wrong powder, or put the wrong bullet in, or mixed powder, because they didn't have their bench clean.
Thats what i can think of right now for the little extras