It's fine, even hoop companies will gaffer the inside of the hoop for grip instead of sanding.
Depends on the designs and kind of tape. Like if you only used a heavy, thick tape like gaffer and taped the whole hoop with it yes it will weigh it down and effect the hoops response time. However, if you use a thin, light weight tape like mirror or holographic and taped the whole hoop it would add such a small amount of weight that it does not effect the hoops response time, in my opinion. That is why people generally only use a strip of grip tape or strips/bands or single spiral of gaffer.