I strongly reco the Dr. Slick tool kit, sold through Cabela's and elsewhere. Good quality tools and a good value. Not mentioned in the catalog is that two of tool handles have half-hitch tools in them and, when you remove the foam that holds the tools, you'll find yourself with a nice fly box. You may want to add more tools over time, but the Dr. Slick kit has all the basics you really need.
I don't recommend anybody's materials kit. Too much stuff of mediocre quality and stuff you'll likely never use. Figure out what flies you want to tie and buy the materials needed for those. Add to your collection as you tie new patterns.
I have yet to need a sinking line for the fishing I do. Sounds like the Cabela's guy was trying to save you some money. A floating line with split shot on your leader will serve you well at the start. Buy a sinking line later if you find you need/want it.
Enjoy!