Thanks for pointers on those issues of concern. We have made some machine automation improvements in GC3, but I will review this again before the next GC3 update.
Please explain what is meant by "ore processing chain doesn't fit into the usual modpack gameplay at all", I don't understand that one? These days Galacticraft ores are all Oredict compatible (unfortunately it was not the case before around version 2.0.10) and the three standard metals (copper, tin, aluminum) should interact fully with other mods. In GC3 we have also added intelligent metal block recipes, so 9 IC2 copper ingots will make an IC2 copper block, but 9 Galacticraft copper ingots will make a Galacticraft copper block. In GC3 there is also a config option to set ores from any other mods to be added to the worldgen on Moon + Mars.
If there is a further thing which will help integration in 1.7.10 modpacks, we will happily include it but I need specifics please.
Our intention is that GC3 should integrate smoothly with IC2, Mekanism, Thermal Expansion, Buildcraft, or EnderIO. (There are current issues with EnderIO2.2 because we built Galacticraft for compatibility with EnderIO2.0 not EnderIO2.2, but that will be fixed soon.)