my question is a simple one:

do shield chargers or riot armour stack...

e.g. if you have more then one shield charger equipped does it charge more?
?

Yes, both stack.

On harder levels where you cannot just walkthrough, I always use the 3 x Shield Chargers and 1 x Emergency Repair (except on the last mission of each Episode). This way, once you clear out a room, your shield is recharged.

On the last mission of each Episode, I use 3 x Riot Shield and 1 x Emergency Repair. Since the last stage of each mission flows over to the next episode, you need to stay alive and recharging your shield is not the most important thing.

When using the Riot Shield, make sure to always stay front of the attacks, try not to get hit from behind. With 3 x Level 8 Riot Shields, you can take almost double the damage. :-)

sweet, so does that apply to cash and rare weapon sensors!? lol

Yep, everything in the game stacks!

wow this game is even better than i thought now lol. and i think its amazing