I think you are asking if you can get adsb weather and traffic to display on the Garmin screens with the GRT adsb setup, the answer is no. If you want to display weather and traffic you must have a GDL 39 or GDL 50. (any variant). Garmin uses a proprietary protocol for this function so you have to have Garmin.
As far as the temp probe, I miraculously found a used GTP 59 for about half the price of a new one, however since I did my install I discovered there are alternatives. I believe in the Garmin G5 manual there is a reference to a few other probes that will work. There is also a pretty good diy solution, see link.
One other thing to consider if you have only the screens you will need to get a configuration module for each screen, you will need to go through a Garmin dealer for these.