Do you need to be 290 or higher to run the raid ?
Well yes and no. What I mean is you can enter at mid 280s and make it through the totem door encounter with a good group if you can stay alive. The bosses really do require 290 to do adequate damage. You are on a timer and you only get so many turns before you either kill it or you wipe.
What some people have done is enter at around 286+ and hope for a ghost shell from the first chest after completing the totem door. That is sometimes enough to bump you up in light level for the bosses. If you have a super group you can be sherpa'd through war priest but beyond that you need to be able to hold your own damage wise. So what I ended up doing is court of oryx and strikes to get a bunch of blue and purple gear to use for infusions or to wear. Ended up at 297 from that alone.
If you need help with anything on the ps4 version I am willing to do what I can to get you up to speed. I can help you hunt calcified fragments, quests, court of oryx, missions, strikes etc. just send a message or a party chat invite so I know what's going on. This applies to anyone playing Destiny on ps4. I actually don't mind running through stuff I have done before when there is someone else there as well. It's a much more enjoyable game with a friend or two, even if you are just doing random quests and patrols. Every enemy is a chance for engrams and every ultra I kill with a 3oC is a chance for an exotic anyway.
My psn is cmdrdredd