I've built a mountain bike and flat-bar road bike piece by piece (and still have a touring bike project in boxes at the moment).

First, from what I've read, the frame geometry for a bike is specific to the type of bars you have. It's not recommended to use drop bars with a hybrid.

Second, if you buy a road crankset for a hybrid, there may be a chance that the crank arms may hit the chainstays. (Road cranksets are closer to the frame, while hybrids are made to accommodate larger tires.)

Third, I didn't find a 105 flat bar shifter on the Shimano web page. This means if you've already ordered 11 speed 105 components, they aren't going to be compatible with 10 speed Tiagra components (where flat bar shifters are available).

My flat-bar road bike has R400 series shifters with R400 series front derailleur (Tiagra equivalent) and Deore LX rear derailleur. It shifts beautifully but when I converted a bike I found on clearance at Canadian Tire (for a winter bike), I changed the grip shifters to Shimano Altus 7x3 speed (found on eBay), installed Shimano Acera V-brake levers and regular-sized grips. I was amazed how well the Shimano Altus shifters worked with the Shimano Tourney derailleurs. It's almost similar to my higher-end parts. So, you ought to be able to do this cheaply.

It's also true like someone said, if you want to change from a 7 speed rear wheel to more speeds, you may have to change the rear wheel.

Why don't you want mountain/hybrid components?

Some places I've ordered from in the past: bike24 (Germany), Rosebikes (Germany), xxcycle (France), Chainreactioncycles (England)