wheel size how to know

these are newbie questions, please help me

 how do you know your wheel size? is it the wheel diameter size (650 o 700)?  or how do you know?

Wheel diameter - just measure it.

do you use compact (50/34-6) or usual 53/39 (mine)? 

53/39

also what casette do you have? ¿11-23?

12/26.  I have been thinking about going to a 11-23 because it is very flat where I live in Florida and I really don't need the 26T cog

do you wear sunglasses during biking? any recomendation?

I always wear sunglasses.  I wear contact lenses and they help to keep dirt, sand, bugs and such out of my eyes.  Got my from Bike Nashbar online for about $30.  They have three sets of lenses - dark, amber, and clear - easy to change out for different conditions.

I have some gallings, burns, contusions, and some zones I do not have skin, I am using betadine, what do you use fot those? (because betadine stains too much)

Can't help with that