For thrust....yes, just about all planes need down and right thrust. Some as little as 2 degrees. Reason for this is engine torque.
If you had a plane with the thrust line perfectly straight, once you take off, the plane would most likely pull to the left, this is because of the torque of the engine. I'm sure someone else will chime in and have a better explanation than me.
Antenna routing. Mostly on glow aircraft, especially arf's, there is a tube that runs from where the servos are mounted and rx to the
back of the plane (inside the fuse). You would thread your antenna wire thru this tube. However, my U Can Do, I routed the antenna out thru the on/off switch hole and to the back. So, it depends upon which plane you have.
Expo on radios. Usually on mid to high end radios. My Hitec Flash 5 has it and so does my Futaba 9C. Expo is very useful in new planes where you set up your control throws and add expo in. It works by slowing down the response or movement of the control surface by proportion to the stick movement. Example may be....you move right aileron (right stick) 3/4 of full stick movement, and your control surface only moves about 40% instead of the 75%...but as soon as you go past the 3/4 of full stick, then the aileron moves much faster to its full amount. This is very helpful when you are getting used to a new plane. I have expo set on my U Can Do and my H9 Twist as the control surfaces on these planes are very large. Hopefully, DBCherry and others will chime in and add to what I've posted. Those guys helped me out tremendously! And I am still learning too!

Dave...