A ship the size of the Raven being seoaration-capable? I dunno... seems kinda iffy to me... in any case...
1- Basic shape of the original Raven, but streamlined, as already mentioned.
2- Similar torpedo grooves to the Defiant class... you know, how there are those pod-like things on either side that seem to house the launchers? Something like that...
3- New shuttles! We're really lacking in new-era shuttles at the moment.
4- I don't personally agree with MVAM on a ship so small as the Raven, especially given the overall design... it just doesn't flow in my mind like it did with the USS David; On a similar idea, have the nacelles inset into the hull. When they'd want to jump to warp, the nacelles would then "pop out" of the hull in a similar fashion to Zepheram Cochrane's (sp) warp ship... I saw a sketch of something like what i'm thinking elsewhere, but I dont remember where I saw it for the life of me... 'twas a long time ago, but it was a really cool ship...
5- minimal weapons; SMALL phaser strips, kinda like the little things that shuttles have... just short little strips here and there. I'm not even sure that a medical ship like this should even have torpedo bays, but that's entirely up to you, I guess... maybe instead of torpedos, just have some pulse phaser batteries like the Defiant.
good luck.
-Aeries.