I would suggest starting with the John Deere website as they have a tool to help select size based on your usage. You can also go to the other websites to get a feel for the prices. Kubota has a "build your Kubota feature" to give you a list price and you should be able to get a fair amount off that. Then start visiting some local dealers and sitting on some of their models. No amount of reading will substitute for sitting on them and at some point driving them around in the dealer lot. That will give you a better feel for what you would like and what "fits" you and also a feel for the dealers and how you get treated.
On the information you provided, it would seem like the Sub CUT size would be a good fit. But for some reason you may fall in love with the bigger size CUTs.
I would definitely buy it with the loader. If you are going to finance, you can include that and most offer 0% now but also that guarantees that you are getting one made for your tractor. It will fit right, be sized right, and will easily go on and off. If you are going to have a MMM, I would buy it then too for the same reasons. Also, if that model tractor is discontinued in the future, you may or may not be able to get those attachment.
Any of the 3 pt hitch stuff, it doesn't much matter, although again, if you are going to want to finance it, you may be able to package it in.
As far as least expensive, as others have said, there is all kinds of ways to define that. In general, there are some tools that I buy at Harbor Freight because I don't want to feel bad if I loose it in the weeds, and there are other tools that I am more concerned with the quality. You will probably have to sort out which kind of tool this is for you. In the end, there isn't going to be a lot of difference in initial cost, so I would tend to get what I wanted within some reason.
Also, as has been mentioned, unless the daughter and friends live next door, your going to need a trailer. I use a tandem axel 16' trailer which I pull with a pick up with a V8 for my B2920. With the front end loader and any attachments on the back, that is about what it will take.