Not all cream ale, IPA, lager, etc, recipes will be the same.
Extract is essentially malt sugar, which the yeast will consume to produce carbon dioxide, alcohol, and other compounds that give beer it's flavor.
The more extract, the higher the ABV will be. But, LME and DME are not equal in terms of amount of fermentables by weight. Liquid Malt Extract contains water, so you will need more LME by weight compared to DME to get the same amount of fermentables.
You don't have to use both LME and DME, per se, but there's nothing wrong with doing that. You can use one of the other, but of course there are different varieties (light, gold, etc). LME has a shorter shelf life than DME, so be sure to check freshness dates when purchasing.
Cream ales is probably a basic enough style that it doesn't need any steeping grains to add different caramel, bready, roasted, or nutty flavors.
John Palmer's How to Brew is a great resource, and free online.
http://www.howtobrew.com/
Another Noob question:
Hen brewing extract is there a set amount of extract in Lbs that is required.
I have read a recipe for a cream ale, by 3 different companies.
Each used a different amount of DME.
DME & LME combined:
5lbs
5 1/2 lbs
6lbs
Just confused as neither of these recipes uses grain, but they all vary in extract