My cousins lives in Orleans that's why i thought to spend 5 days there. I was thinking of stopping at Orleans on my way to Paris from Rome and spend 5 days there and then go to Paris for 2 nights.>

unless you are kissing cousins reverse that - two nights in boring Orleans and five in Paris.

Easyjet looks pretty attractive. But i heard baggage is an issue with them and only 1 piece hand carry of 8 kg is allowed is allowed. and check in baggage would make the total cost extremely high.
is that so???

Looks like a checked bag is 18 Euro, making the fare 45 Euro.

Check out Vueling as well for airfare.

My understanding is that carry on luggage on EasyJet is limited by size, not weight.

flying is by far the cheapest way between Rome and Orleans - train fare would be at least 100 euros p.p. if you go the deepest discounted tickets.

Here are the rules for carry-on:

Option 1: ONE piece of cabin baggage no bigger than 50 x 40 x 20cm including handles and wheels. Guaranteed to always travel with you in the cabin.

Option 2: ONE piece of cabin baggage within our maximum allowed size limitations, 56 x 45 x 25cm including handles and wheels. On some busy flights your bag may have to go into the hold, at no extra cost.

plus, on the Rome -Paris route, a bag weighing up to 20kgs will be taken in the hold for €20.

even so, flying should be a lot cheaper than the train.

I don't think Orleans has an airport so, if you wish to fly, you probably need to go to Paris first and then somehow do a round trip to Orleans.

Closet airport to Orleans for passenger traffic is probably Orly - about 50 miles away.

Bourges and Tours do have regional airports I think but the cheapest way by air is to fly to Orly perferable then take the train to Orleans.

Orleans actually does have a huge airport but it is a military airport only! During the last Gulf War start I was living near it and a constant parade of planes - American, Brit, French, etc were taking off. But alas no commercial traffic!