I was not familiar with the term feminalia and thought to myself, "Why are Romans wearing female clothes?" Also, I am familiar with bracae / braccae which were the trousers I thought Romans wore. So, I turned to my favorite source of all things Roman - RomanArmyTalk.com and found out some interesting stuff:
feminalia is not related to feminine, but the Latin for femur - femen
feminalia are tighter fitting and possible not as long as braccae.
feminalia might also truly be trousers where braccae might be leggings held up by straps, but this is controversial about braccae
Doesn't look like either had inseams.
There is debate about whether they were introduced by Augustus who did not like the cold, or later as the Legions spent more time fighting up north and long socks and boots combined with longer thicker tunics no longer provided enough warmth. The third option is they never really took off until the late Roman period where Legionaries started looking more and more like the Germanic tribes that they were increasingly drawn from.
Lastly, it does appear that within the re-enactors and associated historians who interact on RomanArmyTalk.com that they favor drab colors over brighter colors including blue and red. Although red does appear more popular than blue.
Just FYI since my curiosity was sparked. Lastly, most of the sources for this are limited so this is more consensus of serious/history based re-enactors, several historical fiction writers and accredited historians who interact on this site.