I too find IB a bit confusing, to say the least. However I set up the screen and adopted steps that allow to (almost) eliminate any confusion as far as sign of the operation and whether I need to buy or sell. I don't do it from strategy builder - that screen is somewhat inflexible, I do it the following way.
First and foremost, definitely set up several tabs in the Monitor pane. One of those I use as a scratch tab, where I quickly build spreads, generate orders from them and discard.
In that tab click on an empty row, enter symbol and select Combinations and then Option Combos (SMART) or Option Combos (Directed).
In a Combo Selection window build your combo. As a matter of fact Calendar Combo is quite straightforward, you specify front and back months, put or call and strike - you are done. Vertical spreads are a bit more confusing, since they will only allow you to build it one way - for call you gotta guy lower and sell higher strike, for puts - all the way around. And that's exactly opposite to what you'd want to do when you are selling an iron condor; basically with this setup they are guiding you to build spreads to buy one
Now next info screen shows you exactly what will happen, i.e. which leg is gonna sell and which is gonna be bought when you buy or sell added combo. I'd compare that with the screen Kim posts and that will tell you whether you buy or sell the combo.
Now all you need to do in your scratch tab click on the added spread (make sure you click on the right row, since it adds spread, underlying symbol and each leg) and press small buy or sell button shown atop of the popup menu. That will populate your Order Entry window where you will need to set QTY and LMT PRC and submit your order.
These are probably more steps than needed to quickly create a spread order, but at least it eliminates all the +/- confusion.
PS: I also find it much easier to open an IC in 2 transactions, where I sell CPS and CCS separately. Since IB doesn't charge a ticket fee, the price is same, but you have much more flexibility in getting the right price.