There is no question that a flintlock is a bit more challenging. But, with some reading and with some help from all of the folks on this forum, you can master the flintlock pretty quickly. The loading is exactly the same as with a caplock except that you cannot use any of the substitutes, you must use black powder. None of the substitutes will ignite reliably in a flintlock. With that being said, the only difference between a caplock and a flintlock is in the operation of the lock. There have been many studies done in how to place the powder in the pan. I think if you just level it in the pan, you will get reliable ignition. You can use either 4f or 3f in your pan. Both will work fine. When you build your rifle, make sure that your touch hole is centered on your pan and level with the top of your pan. Your flint needs to be sharp and of the proper width. Some recommend that the bevel of the flint bu up and others will tell you it should be down. There is no right way for all flintlocks, just see which way works best in yout lock. If you have been getting good ignition with your lock and suddenly it starts misfiring, check your flint to see if it needs knapping. Re-knapping your flint is something you will have to have someone teach you. Our late friend, Paul Vallendigham, has a tutorial on the forum on how to re-knap your flint. You need to read it. When loading, it is a good idea to place a piece of wire in your touch hole to keep your powder charge from plugging it. When you get ready to charge your pan, remove the wire and put it where you can find it again.
I know I haven't covered everything but I have given you a good start in becoming addicted to the flintlock like so many of the rest of us have. It is a bit more demanding but you will love it. Do not be afraid of a flintlock, they are a lot of fun. When questions arrise, just post them on this forum and you will get plenty of great answers.