as mentioned, many processing offices require originals... if it doesn't specifically say copy in the country specific checklist for your office, i'd send the original... quite often where it doesn't say original or copy, they will request the original anyways, so you could be saving yourself a step... we did this and were thru much faster than the 30% timeline quoted for our office... unlike what was said above, all originals and every other paper we sent them was returned to us... we put in ticket stubs from attractions we had gone to together, and even they were returned... i have heard of them loosing items, so if you can get duplicate copies of originals (if you are ordering them anyways) it might be a good idea...
as far as the medicals, who is sponsoring whom? if your husband is the sponsor and you are the applicant, only you (and your dependants, if any) need to get medicals... if you are the sponsor, only your husband (and dependants, if any) need to get medicals...
make sure the medicals are done at Designated Medical Practioners
hope that helps