The Imperial Navy troopers , that are the support troopers in FS, performed numerous duties. Combat, security, hangar duties , logistics etc

The support class in FS isnt an engineer only(besides, the Deathstar gunner was only used as an engineer in SWBF2) He supports all facets of combat, performing various duties in support of the main troopers. Thus the reason the Navy Trooper was chosen for support.

As for the Medic. I think it looks alreet. Got a feeling it would look much better in reality (well, not in cartoon anyway) . Tho as far as lore goes and people going "wtf a green stormy!" , I'll just leave it there.

'Imperial gunners were members of the Imperial Starfighter Corps who manned the various weapons of the Empire's capital ships, military bases, and, most famously, the Death Stars.'

They appear as engineers in Battlefront but that game is hardly canon.  It always puzzled me why they were included in it.

medics look ugly, give me regular stormies

Deathstar gunners in Endor or Tatooine? NO.

And the article.

http://starwars.wikia.com/wiki/Imperial_Surgical_Corps

They probably shouldn't be used on the snow maps like Rhen Var or Hoth though.

Also the Support class should imo look like the Enginner from the films. Here's what they look like but I'm sure most of you know how they look already.

http://starwars.wikia.com/wiki/Imperial_gunner

These wouldn't be used on Hoth, Rhen Var, or Endor.

I think it would be more accurate to replace the in-game storm trooper medic and support models with these.