The Storm Troopers are the main case here, they get killed easily by blasters and even the Ewok arrows go straight through their 'armour'.

The AT-ST and AT-AT use armour to repel blasters of different strengths so they don't pass through all materials. I understand though that the armour used on these is likely much heavier.

From the prequel trilogy we also have the droidekas, which have a shield when not moving. Does anyone other than these droids use this technology?

You may use any of the Scrapped EU, Current EU and the normal U to answer.