Depending upon where you live and how far frost goes down will be a factor in any foundation. Also if you are attaching this to your home you will want a foundation. You may not need to take the bricks up to install a foundation, It could start where the brick now ends. The wires you have found may or may not be a problem, depending on depth and what they go to. I would try to keep the present patio if possible and incorporate that within a structure. I think your questions are just starting, you might want to get ideas from several contractors.

thanks roseguy. I am in suburban Chicago, zone 5. So I think frost line is somewhere like 30-34". I will follow up with a few contractors

I would not reccommend putting up a building over top of electrical supply lines. In fact, it is probably against building code. You need to find out exactly what those lines were...perhaps they were actually telephone, cable or internet lines?...and question and discuss what your local building codes are with any prospective contractors.

Yes, you will more than likely be required to get a building permit to build a structure attached to your home. You will want to build a footer around the perimeter below your frost line, especially if you choose a glass greenhouse. The freeze / thaw cycle can cause the glass to break if the foundation is not properly installed. This can be a problem even with polycarbonate greenhouses. I agree with wyndyacre that you need to research the lines some more and find out exactly what they are. It looks like you have quite a bit of space in your yard. Have you ever thought about doing a freestanding greenhouse? I know it is not as convenient as walking out your back patio door, but it would be another option.

u can build a portable green house. i use this one and i works perfectly during summer! I break it down and stash it away during winter. It also makes a mean tent for camping. https://weatherport.com/products/greenhouses/backyard-greenhouse/