From Arduino to production

Hi guys I have been building on Intel Galileo and Arduino Uno for a while now, I have a number of projects made an now looking at the next steps, first transferring to a bread board to make it standalone, then beginning looking at getting PCBs made.

The issue is all of my projects are programmed using Python, they use MQTT as the underlying communication to other devices I have built on my network and one of them uses the Electrohouse NFC module 3. I am planning on using an ATmega328 on the bread board design so I guess I will have to reprogram everything in C is this correct? The Intel Galileo uses the dev kit with various sensors is it possible to use these sensors on the bread board design ? I am guessing it is but guess I would need to write my own native C code for the ATmega328.

I understand the process quite well of starting to move to a standalone bread board, but could do with some suggestions. If everything does have to be C what IDE can I use to program the codes onto the Galileo and Arduino Uno? I had moved totally away from IDEs and been programming Python working directly on the boards through Putty but guess I will not be able to do this anymore once I build the breadboards.

Will all of the modules that I have purchased previously and others work on a standalone device and when moved to a PCB or will I need to look at other modules and sensors.

Its a bit of an anticlimax really, I have just spent a year programming a full network of devices and was at the point where I only needed to create casings before I have my commercial products and then found out that it isn't really a good move to create commercial products using these technologies, I would of preferred to just go straight to programming on breadboards and learning that way.

I guess a good question would be could I skip going to standalone breadboard -> custom PCB and just release my products using Arduino/Galileo boards and sensors or is it required to go the standalone way ?

Will all of the modules that I have purchased previously and others work on a standalone device and when moved to a PCB or will I need to look at other modules and sensors.

Yes they will work.

I guess a good question would be could I skip going to standalone breadboard → custom PCB and just release my products using Arduino/Galileo boards and sensors or is it required to go the standalone way ?

You could use the existing boards - they will be more costly once you go into production, and you will be at the whim of the supplier as to whether they be available, or in sufficient quantity. If you control your own design, then you control your own production.

OK great thanks, I have been doing some more research recently, if I get a chip already with Arduino bootloader can I still program by other means onto the board, I see that the Atmel IDE has the option to import Arduino sketches and convert to code for the chip, if the chip is already setup for Arduino does it stop the ability to program from other sources onto the chip.

If you make the ICSP pins accessible (SCK, MISO, MOSI, Reset, Vcc, Gnd) then you can connect a Programmer and put new code into the chip.
Or make the Serial pins accessible (Rx, Tx, DTR, Vcc, Gnd - aka "FTDI Header") then you connect a USB./Serial adapter and download new code into the board.