Your Defy is a road bike and probably has 130 mm rear dropout spacing. Most current CX/touring frames are spaced 135 mm so you will have to respace your rear hub or get a frame that accepts 130 mm hubs. Some Surly frames are spaced 132.5 mm and will take either width hub with no problem.

Since you already have a 105 crank get a new frame with an English threaded bottom bracket and you can change over the current crank directly with, at worst, needing Shimano threaded bottom bracket cups.

As joejack951 noted, your current "short reach" caliper brakes are unlikely to work on the new bike. You will need "long reach" calipers or possibly even cantilevers or V-brakes depending on the new frame's brake mounts. Even disc brakes aren't out of the question depending on what you buy and these will require a completely new wheel set.

This will be an interesting project and can be a fairly straightforward conversion or a rather expensive one depending on what frame you buy.