Favored window sizes and opening directions?

I'm (re)considering making my own doors, instead of buying manufactured Doors. I want the doors to be larger than 26" wide by 32" or 36" tall which are fairly standard sizes for manufactured teardrop trailer doors. My Benroy(ish) trailer will be 5"4" wide by 10'1" long with two doors. I'm contemplating building the doors 32" wide by 38" tall. I'm 6'4" tall and want to comfortably and easily enter or exit the trailer.
I may buy windows from Vintage Technologies. Their windows come in many sizes. Most can be be purchased as either horizontal sliders/opening or vertical sliders/opening.
The smallest window I'm considering is WD07 that's a 21" wide by 14" tall horizontal slider (with ~ 294 sq. inches of glass). The biggest window I'm considering is WD10 that's 20" wide by 30" tall that opens vertically (with ~ 600 sq. inches of glass).
What are the optimal/favored window sizes for light, views, ventilation, and rain resistance?
Are horizontally opening or vertically opening windows preferable/better? Why or why not?
Horizontal windows may optimize your view.
Weatherproofing and rain resistance may be better with a vertically opening window.
I'm unsure which way windows open would be better for ventilation.
I will have a Fantastic Fan/vent in the roof to exhaust warm/hot air.
I'm also considering whether, or not, to install a Stargazer window, either the 45"W x 9"T WD12 or the 40"W x 9"T WD12-01. If I do it would be installed in the transition area that curves above front wall to the roof.

I may buy windows from Vintage Technologies. Their windows come in many sizes. Most can be be purchased as either horizontal sliders/opening or vertical sliders/opening.
The smallest window I'm considering is WD07 that's a 21" wide by 14" tall horizontal slider (with ~ 294 sq. inches of glass). The biggest window I'm considering is WD10 that's 20" wide by 30" tall that opens vertically (with ~ 600 sq. inches of glass).


Horizontal windows may optimize your view.
Weatherproofing and rain resistance may be better with a vertically opening window.
I'm unsure which way windows open would be better for ventilation.
I will have a Fantastic Fan/vent in the roof to exhaust warm/hot air.
I'm also considering whether, or not, to install a Stargazer window, either the 45"W x 9"T WD12 or the 40"W x 9"T WD12-01. If I do it would be installed in the transition area that curves above front wall to the roof.
