At least from the ingredients you've listed, you might want some more extract if you're making a 5 gallon batch. From the extract kits I've done, there is at least one pound of extract per gallon. I would recommend looking at other recipes of the size you're planning to get a handle on it that way. LME and DME both get used a lot, so knowing how to convert quantities of them for your recipe can be helpful (using brewing software to do the calculations for you is also very common/helpful, especially if you're not doing 5 gallon batches).
A pound of Carapils is maybe okay in a 5 gallon batch but you would want to use much less if you're making something smaller. As Robert mentioned, keeping your specialty malt (Cara- malts, chocolate malt, roasted barley, etc.) to at most 10% of the overall malt bill (by weight) is probably a good rule of thumb while you're getting a handle on the brewing process and figuring out what you like.
As for mixing the DME, I find it useful to look at the Breiss website to see what the extracts are made with. While you don't to concern yourself too much with this as new homebrewer, it might give you an idea of how many different things you'll be adding and it what percentages. As you learn more about brewing and the different ingredients and process you can get a better idea of how to use your extracts and what beers you can make with them. Given what you have I would probably just add all of both but if you end up getting more extract you might want to just get more of one (probably the Pilsen?) and let that be the bulk of the fermentables.
As for including some rice syrup solids, I could maybe see adding some to lighten your beer a bit but I'd encourage you to forgo it at first and see how close you get to what you're looking for with malt extract and then adjust from there.
Also, if you are doing a small batch, I'd be careful about using the whole ounce of hops for your full boil, you will want to scale that down with the recipe size as well.