What would be the head circumference maximum that would comfortably wear these glasses?

The beauty of these glasses is that the TEMPLE (ear) part is adjustable! They "clic" and stretch to fit almost any size head!

Where are these readers made?

USA patented invention; company now owned and operated in Wisconsin; lenses made in South Korea; frames and final assembly in Taiwan.

If you are referring to the size of the frame, then this is the standard or Original frame which fits most people. The length is adjustable on the sides by about 10 mm. If you need a larger frame then you need to look for the CliC XXL (also called XL or Expandable in different listings). The XXL is wider, longer, and has an expandable section in the back of the headband, and is available in black, dark tortoise, and transparent smoke gray. If you only need a little bit longer frame and do not need the extra width, then you can also look for the CliC Long. The CliC Long is usually only available in black. A few very small women may need an even smaller frame than the Original, in this case you would look for the CliC Petite.If by size you are referring to the magnification of the lenses, the standard magnifications for the Original frame are 1.25, 1.50, 1.75, 2.00, 2.50, 3.00, and 3.50.

is this available in 2.0 strength and regular size

This listing is for the regular size (Original) and appears to be for the 3.00 magnification. Yes this item is available and in stock with us (LittleGorgeousThings) in any magnification from 1.25, 2.50, 1.75, 2.00, 2.50, 3.00, and 3.50. Unfortunately Amazon's product database for the CliC product line is full of errors and confusion. Here is a link for the regular size in 2.00. http://www.amazon.com/gp/product/B0006I8I32/ref=s9_simh_gw_p364_d0_i5?pf_rd_m=ATVPDKIKX0DER&pf_rd_s=center-2&pf_rd_r=1ZY1CR43BJNDKHE3DFM0&pf_rd_t=101&pf_rd_p=1389517282&pf_rd_i=507846 If you choose us (LittleGorgeousThings) as your vendor, we offer free 2-way exchange shipping in the event you need to adjust your frame or lens to a different style or strength.