...need to edit things like ad breaks and segments I don't want, will a machine like that do this....
Yes. But usually not wholly seamlessly. Playback usually involves a brief pause, at the edit point. (Like a layer change, if you know what that's like).
So the basic process is - record it, tape by tape (unattended) onto the box's Hard Drive. Edit the recording whilst on the Hard Drive. Then copy the end result to a DVD. The precise details of this process will vary from machine to machine. But in general, this last step is done "high speed" - takes only around 15 minutes and does not degrade the result (digital copy).
Then make a second copy onto another disc or other medium (for backup).
If you want seamless editing then the edit will need to be done on a PC. But even so, doing the initial capture on a table-top box is still my preferred approach for the reasons already stated.
And as a recap - if you already have a good, working VHS machine, then I suggest you don't need to go and buy another, and that includes a combo box. You only need a DVD recorder (with a Hard Drive) and some cables. Given that (presumably) once your task is completed, your VHS component will become redundant, any expenditure on new VHS capability is wasted in the long term. Whereas the DVD recorder will continue to serve, eg for recording TV programmes etc going forwards. Now of course if your VHS is already dead or dying, then it's a different matter.
You can get the unedited data off the box's hard drive, into a PC, edit it and create a disc, all without any further encoding (so, quickly and without degradation) if you use the right methods and software. Again, precise method will vary by machine.