200 2.8 vs 180 Macro
The Canon 180mm f/3.5 can be used with Canon teleconverters, at least with the TC II series.
This is not a good lens for hand-held near-macro and 1:1 work. A monopod works fine, a tripod is even better. I haven't tried the "Lord V beanpole" technique yet on this lens. One gets a thin but sturdy pole (eg tall garden stake) and grabs hold of it with a finger or two of one hand, using the other fingers to hold and operate the camera. Fine focusing can be done by leaning the pole back or forward slightly (millimeters), height adjusted by sliding finger up or down the pole. I gather that the advantages of becoming proficient with the pole method are that it allows you to get into tight spaces and that it is speedy, so insects aren't as likely to finish whatever they were doing and leave.