Right now while I'm learning I want to get away with the cheapest, but I also don't have to have to spend more in the long run because I'm a cheap now. You know what I mean?
I do lnow what you mean. However your idea of the long may not be what you expect.
You could (and IMHO should) use your trainner for as long as posible.
You should also know right up front that each plane can have different engine radio requirment. Read this as for each plane you put in the air you buy an engine and flight pak (Battery, Servos, Rx) Some people even buy the transmitter (I have 8 6 non computer 2 computer)
If you want to enjoy this focus first on getting the first plane and learning. You can allways sell it or its parts to fund later projects
There is no "magic" formula when starting out and trying to anticpate where you will be "later" on can drive you mad..
If you want to fly the 4*60 as plane number 2 and don't want to have to buy a second engine then go with a .60 size trainer
Problem with this is it leaves you with only one flyable plane.
Who knows you might find out that this isn't for you?
Bottom line is no amount of questions is going to give you 100% accurate info.
My suggestion is get into the air fast stay in the air and take the hobby 1 project at a time.
In the 19 years I've been doing this I can honestly say that every plane I've owned has costed me something to get it airworthy. Its part of the hobby.
As far as the Wife is concerned here is some more free advice everthing costs 20.00 and pay cash when ever possible (no paper trial)