A friend and I recently started playing Warframe PS4 edition. We're still lvl 0. We're pleasantly surprised by this game and have a few questions for those who play or have played it.

*Is it worth spending money and upgrading?
*Are the upgrades fun to use?
*What advantages do upgrades provide?
*Any particular Warframe or weapon that stands out above the rest?
*The missions have a decent variance but what out the other planets? (We're still on Mercury) What I mean is, on Earth, is there an outdoor environment or is the game strictly a corridor shooter?

Furthermore, if you have any tips, trick and recommendations, I'm all ears

Thanks,
Notorious