I think the power range and specific reticle is more important than SFP vs FFP and MOA vs MRAD for practical application. Many of the Christmas tree reticles at lower power, for me, are close to worthless for using the subtensions as I can not easily read them. For that reason I need the power set up around 12-15 or greater. The reticles with more detail are messy at lower power and more precise at higher power. Actually looking through the scope is important to determine how your eye will deal with the specific reticle at those powers you most likely will use in application.
For most shooters they are either shooting known distances or using a mechanical or electronic ranging gizmo and have no interest in reticle ranging. Reticle ranging is never going to be more accurate than the typical electronic gizmo, unless of course the gizmo isn't working when you need it! But, as you are wanting to learn, it can be rewarding and reasonably accurate if you become good at estimating proportions and performing simple math. Accuracy will start with our ability to first find a subject/target, then closely estimate it's size. If that is not possible, we need an alternative such as a gizmo or be good at estimating distance by football fields!
Hold overs/unders and windage are most often the best advantage for most shooters and we can do that with SFP or FFP scopes provided the reticle has the appropriate subtensions. I've never owned an Arken, but from what I have read and shooters I have talked to, they seem to be more than adequate for your adventure. As others have noted the big advantage of the FFP is the subtensions are applicable at any power where the SFP is only useable at whatever power the manufacturer has determined and if we range at that power we can learn ranging and Holds with a SFP.
As for 1/4 MOA vs tenth Mil, there isn't a lot of difference, they both require some math for ranging, we get to pick our poison. I have always used MRAD/Mils and recently switched to MOA. For me neither seems to have advantage over the other for civilian shooters.
I hope you will update with your progress during your quest to learn.