Your frog looks in the right place to me, (flush when a finger dragged across) and I wouldn't be concerned about having it adjustable. (as it's not a single iron plane)
You will be better off getting your iron sorted first, and seeing if the frog needs some tiny adjustment if it's skewed later on.
If you can get it where it needs to be without it moving when tightened, i.e no blob of paint or lump, then it's likely alright and you might not need touch it ever again,
I might have cleaned them once in a blue moon, say if it were really humid and I seen condensation.
I've never seen/read of a plane that honestly needed real work in regards to the frog being off.
Looks to me the old cap iron is good, keep that stuff, another double iron is handy to have around.
Probably best to see pics of your honing setup.
Does the blade lie flat on a bench, or could it need a tap flat.
The guide might be worth an inspection in regards to it being square when tightened.
This might explain things, cut to the part what I'm talking about.
thanks that's very useful