As far as trouble with large zooms a buddy of mine had a few issues at early rounds but no one has posted any issues of late. I was at St. Louis and there was many 70-200, 300 and 400 f2.8 and even one dude I saw with a 300-800 Canon that looked like a friggen telescope mounted on his camera.
First advice I'll give is get there the moment the doors open and shoot the practices and afternoon qualifiers, come evening put the camera away and enjoy the show.
As far as the 1.4 tc goes, I'd personally leave it at home. It turns your f2.8 lens into an f4 lens and for this situation you don't want to give up that stop and speed. That being said I've never been to Irving stadium but I understand it's open in the centre so you may have way more light than any of the SX's I've been to.
As for the other modes, you really should try to get familiar with your camera but as a way to get out of shooting fully auto preset modes you could start by using Aperature priority (AV mode). Choose your aperature which for most indoor stadiums will be f2.8 or f4 maximum, again you may be able to stop down more if you have alot of light from that hole in the roof. Set your focus mode to AI Servo. Once you set to AV and shoot a couple of test shots if the shutter speeds the camera is giving you are too low then bump up your iso setting. At St. Louis I had to shoot f2.8 with the iso between 800 and 1600 most of the day to get decently exposed shots.
Have fun!