There are no drawbacks to micro chipping – it’s a largish needle that they use to insert the chip under the skin, but the pets rarely react much at all. Make sure that you register with the chip company. I can’t tell you how many injured animals have been brought into the clinic by Good Samaritans whose owners have gone to the expense of chipping but then don’t register their information. We are completely unable to trace ownership without that information. I don’t recommend a collar with tags because cats can be absolute Houdinis about getting them off. If you do use a collar, make sure it’s a “safety” or break-away collar so he doesn’t strangle himself. Cats and dogs do not exchange disease except in rare cases (and rabies). The rabies vaccination is required by law and you can usually find low cost clinics through the local shelter. The first rabies vaccine is good for one year, each one after that is good for three years. The other vaccines should be boostered at least every three years (the veterinary community is revamping it’s vaccine protocols.) While I do not vaccinate my cats for FeLV or FIV, if you’re going to let your cat roam outside, I would strongly recommend that you vaccinate for those disease (feline leukemia and feline immunosuppressive virus). If you cat contracts either of these diseases from an infected cat, there is no cure. Of course, declawed cats should be kept strictly indoors for their own safety.