well bred ratties can see 4-5 yrs, but 2-2 1/2 is old for most ratties.
BUT, these 2 should give you plenty of time and fun to get your thouroughly addicted
with the hairloss id say a quick trip to the vets, its very likley mites and a dose of ivermectin should clear it up (give their cage a good bleach and wash too!)
sneezing for the first 48 hours i wouldnt worry about, ratties tend to stress sneeze, but if theres any discharge id have it checked.
personally id take them to the vets ANYWAY, find a good small animal/exotics vet because many vets havent a clue when it comes to ratties, have them give a good look over just to be on the safe side to set your mind at ease.
generally beyond respitory and mites they tend to be healthy animals, watch for tumors with old age, there especially common in petshop ratties and albinos are especially prone to cancer.
get them on a paper based bedding, pine and cedar are BAD for ratties. and no wire floors (cover shelves with lino tiles) otherwise, enjoy! ratties are awesome! and addictive!