1 server to rule them all using the force while flying the U.S.S Enterprise (or something) The place where I can see the most RP happening would be on the ships, thought it could be possible to roleplay on the ground, its super dangerous with projectiles flying at your face, and you're being chased by giant scottish fungi, sadistic goth hillbillys, and some fancy pancy spaces elves. Not to mention Some giant bugs from the saints row that try to mug you and steal all your bio-mass with their bio-swag. Nuff Said
it's 40k for god sake.... me shoot you in the face and illuminate you with the imperial truth is all the RP we need
If you are worried about immersion...I think seeing bubbles or anything above someones head would take me out of the games immersion. If you can't handle dying so much because it takes away from RP, then honestly this game might not be the best RP game for you. Unless you are awesome at killing nids you could survive awhile. I don't see anybody ruling that battlefield without dying often enough in the PvP.
*plots to get a keyboard attachment thingy for the PS4 controller then* I'd have to agree, most of it would probably be aboard the ships, with maybe a phrase here and there on the actual battlefield. Cus when you're fighting, the only time you really have for typing would be, "Incoming!" or "Left!" or other directions depending on the intensity of the fight at hand. Can see the directional thing happening anyway even if it weren't RP, like for instance co-ordinating with another group a strike on the enemy. "You go left, we'll go right. Blast them to pieces!" That kinda thing. RPing without even meaning to RP.
Some of the best PvPers and PvP guilds I have been around are RP, they take that shit serious son. This IP, I believe, especially lends itself easily to RP. Everything is based of combat, the lore, the fluff, the game(s) and EC will definitely be. So have at it I say. I don't RP myself, but I don't throw mud at those that do.
Doubt they'll use a server exclusively for roleplaying. Like the others before me have said, you'll either have to do it aboard the ships or make it up as you go during PvP/PvE.
Sorry bro no RP server cause one server to rule them all one server to bind them one sever to control them all one server to find them. Ok enough lord of the rings In 40k but yea no speach bubbles. Not only will it break immersion it would also look ridiculous AND it would cause lag with the server and it wouldn't look nice aesthetically.