Welcome! Dry extract is pretty similar to liquid extract. Liquid extract usually comes in 3.3 lb cans. The dry stuff matches at 3 lb. For most batches I use dry because it's supposed to be less likely to degrade in flavor as it ages. Most manufacturers release their extracts in both forms. So when I'm formulating a recipe that involves, say, 6.6 lb of briess gold liquid malt extract (LME) and the store is out, I'll just sub in 6 lb briess gold dry malt extract (DME). They're the exact same thing recipe-wise. They're also used the same. The advantages of DME is that it ages better on the shelf. The advantages of LME is that it is slightly cheaper and is easier to stir in.
A late extract addition involves adding a portion (usually half, some say all of it though) ofyour extract near the end of the 60 minute boil. So you start your boil, add your 60 minute hops and half your extract. Then 15 minutes before the boil ends, add the other half of the extract. This will still sanitize your extract but prevent scorching.
Please don't let this darkness factor discourage you. I have noticed the difference in color between extract and all grain batches. But don't allow this color difference to make you think it has a significant effect on the flavor... some of my favorite extract recipes are cream ales which are very light in color and stand to lose from any roasted flavors. The color darkening is barely noticeable and the magnitude of color change doesn't reflect the magnitude of a 'darker flavor' if there even is one.
I hope this helps, and please don't sweat it. Even the hardened experts here brew extract recipes often and I think that is a testament to the quality of beer possible with extract batches. So don't sweat it, and happy brewing!
