The best way to get combos from team mates is to never buy more than a single power and make sure it combos. The krogan guy loves to spam the shit out of incinerate, which makes combo-ing with him easy (assuming you are going Vanguard).
Also, the jump jet is simply not useful at all on anything above normal difficulty. You are basically asking the enemy mobs to rape you in seconds (they already are hard coded to favor attacking the PC over the party members as it is) as you abandon whatever cover you might have. Its a fun feature, but utterly pointless for combat.
Vanguard with maxed out cooldown reduction is really the only way to play this game in Insanity, unless you want to just roll with it as a cover based shooter the whole way. The problem with trying to be cover minded is that it has the DA2 issue of adds just showing up magically to negate your cover and the added fun of the cover system being completely busted. Really, the best setup for pushing through insanity is Charge with max Cooldown reductions, Nova, and maximized AE singularity with shield stripping. Then dump all remaining points into the combat passives to maximize durability and slot the best long ranged gun you can carry and still not compromise your cooldowns. Mass that Charge button and mele like they were your prom dates love button and hope to Allah that the shield regeneration keeps up with the ludicrously accurate beam weapons. The upside is fighting the whole game like that is actually somewhat fun, at least until you run into all the sync kill bosses (thats what the long range gun is for).
I don't often like agreeing with
Utnayan
on things, but he is correct about the MP. Its basically horde mode from DA:I MP with the knobs cranked to 11. Except there are no good support classes (unlike ME3) and your options are basically Vanguard or turtling.