1) tercios: no, that is not correct in all ways. in battle of breitenfeld 1631 the imperials under tilly use big tercios but the swedens use only 1/3 pikes and 2/3 muskets. this is following the teachs of Moritz von Oranien-Nassau, he reorganise the army of the united netherlands in early 17 jhd. but the first who really use the teachs about this reforms was gustav adolf, and the main reason was the bad basics for war in sweden (the "war industries" was much worser than in other europe, most weapons must buyed). he must use another way of war if he wants to win against the veterans of imperial army. also he had his bloody lessons in war against poland-lithuania.
french army may be good in drill and weapons (don´t know) but the leaders..

2) muskets/reforms: Sorry, the mod is short infront of release. we will think about possibles about formations in patches. the reform we have includes the more strengh of muskets.