If you're just looking to use the LME to boost OG, use some extra light DME instead.
Once you start looking to tinker with recipe's, either someone else's or make your own, you really should start using some brewing software. I go with Beer Smith for my recipe's, so that I know what the product will come out like.
Going with, essentially, a full pound of black malt, for a 5 gallon batch, really is a lot. I wouldn't go with more than 8 ounces, total, in a recipe with 4 ounces being more preferred. Especially if you're not looking for a pucker.
Roasted barley:
"Imparts a red to deep brown color to beer, and very strong roasted flavor.
Use 2-4% in Brown ales to add a nutty flavor, or 3-10% in Porters and Stouts for coffee flavor." With an SRM of around 300, it will darken the brew, but will also give more flavor depth. Right now, with just black and chocolate malts in your grain profile, it seems more of a one note brew. I go for things with more rounded flavor profiles.
I have a stout recipe (an imperial stout, but the grain bill can be adapted to a sweet stout) that calls for:
4 ounces Dark Crystal
4 ounces Roasted Barley
4 ounces Chocolate Malt
4 ounces Black
I pulled the Black from the recipe (don't care for it too much) and just increased the Chocolate Malt to 8 ounces, to have the same amount of grain. I could have split it between the other grains too, if I wanted to.
Looking up a sweet stout in the Joy of Home Brewing book, it lists the specialty grains as:
1# Crystal Malt
.25# Black Roasted Malt
.25# Roasted Barley
Yeast type: Ale
I would also really get confirmation on the yeast number they list, since Wyeast doesn't list it (at all) online... It could be a typo, or it could be a different brand yeast all together.
For a starter, unless this is over 1.060 (like around 1.070+) it's not as needed. Just let the smack pack swell up fully before you start brewing and you'll be fine. If the brew does have an OG of over 1.060-1.070 (or higher) then make a starter (about .25/1.5oz cup extra light DME to ~1 quart water, boiled briefly).
BTW, Dark Crystal malt (120L) would be a better choice, in my opinion...
On John Palmer's site it lists black as:
Black Patent Malt 580L This is the blackest of the black.
It must be used sparingly, generally less than a half pound per 5 gallons. It contributes a roasted charcoal flavor that
can actually be quite unpleasant if used in excess. It is useful for contributing color and/or setting a "limit" on the sweetness of other beer styles using a lot of caramel malt; one or two ounces is useful for this purpose.
Read up on the different specialty malts so that you know what they will do to your brew before you start tossing them in (in random amounts)...
http://www.howtobrew.com/section2/chapter12-1.html
For the vanilla soaking, you can use vodka too. I used about 2 ounces for the soak. I'll know shortly if that has impacted the flavor at all. I kind of doubt that 2 ounces (or even 4 ounces) would impact a dark brew enough to be noticed. The soak was to sanitize the bean before adding it, that's all. I'm not planning on soaking the bean when I add it to the batch of mead I'm making, since it's around 14% ABV already, and should be able to kill anything hitching a ride on the bean...
For hops, it really has more to do with what you're looking to get in the brew. I wouldn't lock myself into just one source for any ingredient. Look at Farmhouse Brewing Supply (
http://farmhousebrewingsupply.com/) for really good prices on hop pellets. Getting them in 4 ounce packets means you can measure out how much you want/need to use and then save the rest... I vacuum sealed mine back up after using them on the first brewing day (keep them in the fridge)... I'm using more today (1/2 ounce Target for bittering, 1 ounce Fuggles for flavor/aroma), and will simply reseal the bag once I've extracted what I need (I have a FoodSaver vacuum packer)...
Before you mess around with any store's recipe, I would suggest talking with them about the changes you're looking to make. I did that at the LHBS for the first couple of brews I was basing on their kits. We would add/replace items more to my tastes than what was in the kit. Kits are usually for the people who either don't want to mess around with recipe's, or are just starting out and need a few solid brews under their belt to be confident in their own ability to make good beer. Once you've gone past that point, you'll need someone with good knowledge to bounce your changes against, or to help pull you back to reality with your recipe.