- You need some kind of audio interface to take the guitar input, convert it to digital and bus it into your computer. There are guitar specific ones that are bit cheaper because they provide only the features needed for guitar and not extra things like mic preamps and different kinds of routing for general recording needs. But a recording interface will work fine as well.
- You need a MIDI controller in pedal form if you want to control the software.
- (If you want to send the signal back out to an amp) you need an output at reasonable enough level for a guitar amp and ideally you'd want the capabilities of a re-amp box (converts the balanced output to the unbalanced guitar amp input eliminating potential hum). In other words you want the amp getting the same unbalanced signal at roughly the same level it'd get from guitar + real pedals. This typically requires a reamp box as I said.
There are some boxes that combine the first two (example only: this or this), but I can't think of one off hand that includes the third as well. You may want to forget combining them into one product and just get separate things that fit both your needs and budget.
So first think about getting an interface that meets your needs for guitar (and otherwise if you have any recording ambitions). Then add in a MIDI pedal. Then if you really need to send it to the amp rather than using a software amp, get a reamp box.
But before you drop a bunch of money, I'd try to test some of the software even if it's with a cheaper iRig type interface to see if you like the sound and feel of software effects and amps. Some people love them but personally I've never liked the feel and response compared to a real amp.