Our Irish Stout is designed to be produced with 500 grams of Coopers Light Dry Malt Extract, and 300 grams of Dextrose. My recommendation to you to create the beer you are looking for would be to adjust this recipe a bit.
Get the Irish Stout kit package, which includes the kit, Light Dry Malt and Dextrose, and also get another 500 gr package of Light Dry Malt. Use the kit, all of the Light Dry Malt and the 300 grams Dextrose. This will give you a bigger, maltier beer.
Good fermentation temperature is critical for quality beer. Different types of beers have different temperatures.
Lagers generally should ferment in the range of 50-62'F (depending upon the requirements of the particular yeast strain). Ales should ferment in the 65-75'F range, again depending upon the particular yeast. I would ferment the Irish Stout in the 68-72'F range.