I should point out that all this gear I used for diving but I did do a fair amount of snorkelling with it too. This is the closest I could find to the kit I own... As you mentioned, they do some pretty decent kits, that's what I bought and the quality is really good.
http://www.tusa.com/eu-en/Tusa/Boots/DB-4000
http://www.tusa.com/eu-en/Tusa/Fins/SF-8_X-PERT_ZOOM
http://www.tusa.com/eu-en/Tusa/Snorkels/SP-240_IMPREX_II_HYPERDRY_ELITE
http://www.tusa.com/eu-en/Tusa/Masks/M-110S_VISIO_PRO
As for sizing, the boots will just be your normal size, I'm a size 10 like you and the size 10 fits well. If you get a chance to try before you buy that could be handy too! But in my experience their boots are true to life. With the fins, they cover a range of sizes so you need to check the individual fin sizing really.. Size 10 is normally a medium/large. They normally say like 10-14 is large or whatever. Because the fin itself doesn't fit like a shoe you can get away with going to the lower end of a size group, for example: if it says medium/large 8-10, large/xlarge 10-12 I'd go for the medium/large.