I believe the micro transactions are purelly for your Avatar/character progression. Not game content as such.
Any thing game related such as Weapons/ammo/Armour/shields and Vehicles (Ground or Air), will more than likely be bought and paid for with ISK from subsequent investment from alliances or eve corps.
Things such as Apartment spaces, Apartment furnishings and galleries for inviting your friends over for a look at your recent victories and such, i would imagine would fall under the micro transaction process.
Perhaps if there were special advancement bonus's that you purchase (like implants) that could effect the max speed of a vehicle or the fire rate of a weapon, then i guess people could invest in their characters, rather than grinding away on missions to earn these bonus's. These would be beneficial if say you wanted your character to get ahead of the influx of merc soldiers on the ground so you can get into your very own MCC and control the battle your way.