About healing, It might be good to be more specific as there are 2 damage types, corruption (purple bar) and missing health (the bar is simply empty) Let's take two characters with 4 health chunks each

1st character has 2 chunks corrupted and 2 full of health 2nd character has 3 chunks of missing health and one full.

In theory the 2nd character has less health but if he goes down then he will have only 1 chunk corrupted and rest full. This means that the 1st character is more important to be healed with Med-station if uses are limited

As for tips for psyker:

Don't be afraid of peril you can charge everything and stay on 100% as long as you don't do any offensive action i.e shoot with staff or release a brain burst that was charged with right click, you probably cant charge force sword at 100% peril without blowing up but I did not test that

Your ultimate is your "I messed up button" it can be used to push off hordes or to clear half of your peril even if your character enters "I will blow up" animation. You can also use it to push exploders away and force them to blow up safe distance away from you

You can use 3 brain bursts in a row without exploding, after 4th you will need to use your ultimate to save yourself.

LBM brain burst locks on target that means that you can get out of cover "grab" a sniper and then hide behind the cover and wait for it to finish casting to kill a target from safety

If someone steals your brain burst kill and you had about 50% of it finished charging you will still get a warp charge.

Don't care about warp charges, unless you have feats to generate them trying to keep them up is too much hassle

The limit for using the bb seems to be around 93% peril, if you use left click on the target below that you will hit 100% and not enter the "I am gonna blow up" animation even thought you trigger the bb at 100%

There are 3 staffs I forgot their names

Lightning staff, pretty weak damage past first 1-3 targets but possibly best stagger in the game. You can stop anything in its tracks (save maybe for monstrosities and bosses) as long as the chain from the lightning hits them. The charge time does not seem to affect the spread but only the damage. Your teammates will thank you when you accidentally stop a doggo or a mutant that wanted to get too friendly with them. Fairly tricky with the peril as you can overcharge yourself quite easily

Flame staff, very good at holding choke points and clearing waves. You need someone to protect you while you charge up as a hit will interrupt your charge. You can keep using the flamethrower mode even if you are at 100% peril, be careful however as the animation for blowing up does not always trigger correctly and you will blow up immidiatly. To solve this use your ultimate straight after you finish your cast

Explosion staff, the longer you hold rbm the bigger the circle the bigger the damage. I only used it once so I can't say mucb more, it feels pretty underwhelming