What about the condom size?

Condoms are made in different lengths and widths, and different manufacturers produce varying sizes.
There is no standard length for condoms, though those made from natural rubber will in addition always stretch if necessary to fit the length of the man's erect penis.
The width of a condom can also vary. Some condoms have a slightly smaller width to give a "closer" fit, whereas others will be slightly larger. Condom makers have realised that different lengths and widths are needed and are increasingly broadening their range of sizes.
The brand names will be different in each country, so you will need to do your own investigation of different names. There is no particular best brand of condom.