If you are shooting in HDV, you can actually shoot either on DV tape or HDV tape. Plenty of people have shot on DV instead of HDV, as it is less pricey.
I have heard that some, if not most Sony tapes use a wet lubrication system, whereas most other companies use dry lubrication. Whatever you use, stay with that one and don't go back and forth, UNLESS you do a head cleaning. If not, you could possible clog the head and it may eat up the tape.
I would get the dry lubrication tapes instead, and possibly go with Panasonic tapes. It's up to you on whether you want to use DV or HDV tapes, but apparently HDV tapes will have less of a chance of giving you dropouts. Again, most people have shot HD on DV tapes and it will work fine, it just depends on how imortant the footage is.
If the footage you are shooting, is just family footage, or just messing around footage, you can go with DV. If you are shooting a wedding, or shooting stuff for a client where you have no room for errors, you should consider the HDV tapes.
As far as re-using the tape, it should be fine, but again, if you are shooting important stuff, such as the wedding, always go with new tapes.