As a first timer, you may not be aware of the time it takes to get around WDW, it's large and to go from your resort to another resort to eat will 100% take away from your goals of hitting the headliners and taking in each country. You can spend all day at epcot with no ADRs and you won't have enough time to see each country and ride all the attractions, it's just not feasible. Having G+ and
DAS will help but having two ADRs will not allow you to accomplish what you are aiming for. You will not know where you're going as a first timer so just navigating the parks and resort will be new for you.
I think a lot of first timers underestimate transportation time, waiting time, how long it takes to walk from point A to point B, meal waits/delays to be seated, etc. Also, keep in mind Space is not designed to be a super quick walk in, eat meal, it's definitely an experience that takes a bit longer than a traditional sit down. I would give yourself at least 1.5 hours for each ADR and that might be light when you add in your drive/wait time. If you have another day devoted to exploring resorts, it might make more sense to move your ADR at GF to that day so you aren't trying to cram two meals into an epcot day.