broken bleeder screws... help?

Is there anything I can do short of replacing the entire heater tube and the ECT sensor/lower rad hose housing? (proper name?) I have broken both somehow!

You could try a screw extractor or drill and retap the threads.

Is there anything I can do short of replacing the entire heater tube and the ECT sensor/lower rad hose housing? (proper name?) I have broken both somehow!
if the head came off with the screw in place leave it alone, otherwise you need to get real lucky with a screw extractor. unfortunately the screw in question is brass, and the extractor will spin right out due to the soft nature of this metal. good luck. FYI the tube is 80 bucks from the dealer.

I'm worried it'll cause me pressurization problems. That and I can't bleed the system like I could before. Well... I suppose I could leave the front-end of the car raised up and try and let it bubble out, if that really works.

I'm gonna go ahead and try and drill it out. I can order new screws for like $2.

You may be able to loosen the hose that attaches to the tube to bleed the air out. May be worth a try before you get the drill out. Seems like using the bleeder screw is a necessary procedure for removing the air from the system though.

Just trying to detach the hoses is a pain! They apparently somewhat fuse to the metal over time. After I replaced everything I suppose it wouldn't be a problem... But still, I'd much rather have them as it's a bit easier than attempting a hose removal & getting coolant everywhere.