• Rotate an object like a building - select the object and then F or G to rotate (during initial placement, hold LMB and move a little before releasing)
• Fix check rails in a junction - Ctrl double left click to bring up options to adjust components. Start off by deleting all then adding N/A one by one and adjusting number to fix.
• To snap to track when track laying one line to connect to another line, press ctrl.
• If you have the snap to track (magnet icon) ticked, you can't get straight track unless you press control (which I think is opposite to the above point).