What should be crossover and speaker size?

The primary reason that you would use a crossover is to integrate your speakers with a subwoofer. Since you don't mention a subwoofer, then you probably shouldn't worry about the crossover frequency.

Set your speakers to small and use the crossover the sounds the best to your ears and in your room. It will most likely end up between 60 and 100. but you will find the opimum for your liking may be dependent on the material. Many times you won't be able to distinguish between the values. Another variable is subwoofer volume. I find I get clearer voices at even higher crossovers and sometimes jack the crossover to 150 just to get a bit more clarity on the voices on my front speakers at the cost of loosing some things in the lower end.

80hz is the generic recommendation, but mileage may vary depending on speakers, etc. Try various settings and see what works best and blends best in your system.