How to build 180 degree turn

Hi,

I am planning my second layout having dismantled the first.

This layout will be in the shape of a letter C or G around the edge of the room.

My question is about the 180 degree turns at each end.

I read 2 techniques somewhere on this forum.

A) use 22 inch turn pieces
B) use flex track.

The smallest radius I will use is 22 inch because we will be running a Bachman Acela which has long cars that hate turns.

Do I have to solder the turns?
If I do solder, do I do this from the side of the track(probably , yes)

The owner of the local train shop said to use flextrack, solder and then make cuts in the track with a dremel (because things expand) and use jumper wires to keep the electricity flowing.

Thanks in Advance,
Peter