(I couldn't send you a PM, you seem to have reached your limit)
In response to your question:
IP and EP together are required for military construction. EP is all that is necessary to undertake projects or programs. Holding a certain amount of IP in the bank will increase your EP per turn (income), but I won't disclose how much IP you need banked, you'll have to experiment.
You may spend all of your incoming EP (EP per turn) during the turn you expect to earn it.