Mapping an Earthlike planet

[Pixie]

Welcome. There are a few around working on the same kind of project that you want (have already) to embark on, at different stages of completion.

So far, your start is awesome. I really like the shapes - diverse in aspect and size. However, I agree with you, the ortographic views of the poles have show Eneage and Ghaon (specially Ghaon) awkwardly tipping towards the pole.
If you search in this, part of the forum you will find plenty of threads devoted to figuring out plausible tectonics, plausible climates, based on the planets being "created". The next step (shall we call it the standard procedure) is to give some thought to the tectonic movements that are forming those oceans and continents.

As for your main question about map size and file size: make several copies of the original land/sea file. One will be used for tectonics/topography, one for climate issues, one for political. These three topics, at least, will already yield many many layers.
One piece of advice though - it will take time to get something really nice and the majority does not get their stuff finished. The thrill is the ride, actually, so... enjoy.