A slime may expand or contract itself and change its shape at will. The smallest you can resize to depends on the item granting sentience. If it is a helmet, then your form may not become smaller than the helmet, and a layer of ooze must be kept around the item at all times. The largest you may become is a thin enough layer to block a doorway, or morph into the shape of an office chair or equivalent size item. 

Your Constitution Score increases by 2

Slimes are dungeon dwelling monsters and lean towards evil, but their hosts may be different. 

Your size is anywhere from 4 feet to 6 feet in your normal form

Your base...slopping around one the floor speed....is 25 feet.

Slimes are typically found in dark, dank, dirty holes or hovels. In order to see the small vermin they typically prey on, they have adapted to gain the ability to see in the dark

Slimes slide around all day picking up god knows what. Because of this, they have gained increased vitality and cell response...or they just don't have to give a shit? 

Awakened Slimes speak primordial, the language of the bodies original slime form, and the host...likely speaks another.