The chance of contracting salmonella from raw eggs is extreamly small, although not 0. However, there are pasteurized eggs available, and if these are used the chance is in fact 0. As far as clarifying agents, i have experience with bentonite and sparkaloid, neither of which i really like. Bentonite settles out extreamly well and is easy to rack off of, but doesn't always do a satisfactory job of clearing in my opinion. Sparkaloid is just the opposite, it produces some of the clearest most beautifully sparkling meads I've ever seen. However, it does NOT settle out well and is very hard to rack off of. i always end up with a fine dusting of it in the bottles. a lot of people recommend using both bentonite and sparkaloid in the same batch (although not at the same time) as one pulls out particles of one charge and the other pulls out the opposite charge. Mind that if you use them at the same time they will essentially cancel each other out.