coolant wont circulate thru engine. overheats

Yes, replace the thermostat as preventative maintenance. These things are prone to actually breaking into 2 or more pieces and parts get caught in the impeller.
Bleeding the air out of the system is tricky but becomes much easier if you elevate the nose of the car as high as possible and follow the procedure found on http://www.e31faq.com under
Engine - 10
17-Rad
Item #1

Do not ever let the car overheat. Very bad (expensive) things can and will happen if you do.

Also, heater core replacement is an easy but intimidating job that a competent D-I-Y'er can do at home. Did one last summer on a 91. With heat (July in Santa Rosa Ca) and lack of ambition, it took us 3 days but could likely be done in 12 hours or so.
Again, see http://www.e31faq.com
Electronics - 60
64 - Climate
Item #1
For more info...

Where are you located?

The E31 Message forum on Roadfly is a great source for tech info. Excellent archives and many owners there daily.
http://www.roadfly.com
Forums
BMW Message Forums
8 Series (E31)

on the heater core note...

i have always had good heat come from the system however it is readily apparent wjen the car warms up enough to produce heat in the cab; there is a gurggling noise that comes from the console, presumably when the thermo opens up enough to circulate hot H2O through the core. does anyon else experience this and is this a sign of a core in need of replacement?

Generally a sign of low coolant and air in the system. Check coolant level when cold, add coolant as necessary. Recheck coolant again when cold over the next few days and top up (to the recommended level).