Dear JAM, especial for you 
Here is my shot 
1) What possibilities will renegade-X offer to spend your money in when the airstrip/war factory and the barracks/HON is destroyed? We know there will be some kind of "call in an airstrike", and the original nuke/ion cannon. But will there also be cheaper investments like buying a package of grenades that you can use? (lets count this as one question :P)
2) Will we see in the future, some extreme tiberium weather effects, like big storms, of ion storms or things like that?
3) Will box-dropping make his return?
4) If they will return in renegade-X, will they look some cooler, and will they have some kind of opening animation when you walk on it, as that boring renegade boxes that dropped.
In some servers in renegade, they rebalanced the game by increasing the prices of units. Like the NOD artillery was 500 and the Stealth black hand was 800. For some reason did this fix a big balance problem. For example there were more NOD players defending, while normally they just where camping near GDI to nuke the hell out of them. Which was impossible when GDI was defending well

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5) Will the NOD artillery have the same amount of damage as the MRLS, so the prices will keep the same?
6) Will the SBH still cost 400, or will it be upgraded to a higher amount, or will they only be able to stealth for a period of time?
7) will tanks automatically be the color of the environment? or will we have the change to decide this for yourself, or will they only have one kind of skin?
8) Stealth tank, keep it red, or camouflage it more realistic?
9) A lot of health is something we saw a lot in the time that renegade was made, will renegade soldiers keep holding this kind of game play? Or will we see some kind of a few hits is dead game play?
10) The barracks, beds to sleep? Yes or no?

11) Will we see rare buildings of renegade? And will we see them more often? For example the tiberium silo, and the repair pad?
12) If you give the tiberium silo and repair pad a comeback, would they also have some kind of weak points? Like the MCT of bigger buildings?
13) Will we see Urban environment in the future?
14) Will this Urban environment, when it will be made, also allow units to enter buildings?
15) Will snow have as side effect that tanks will slide a bit forward when they try to stop? :P
16) Will a crash against a tree with a humvee/buggy be deadly for a driver?
17) Will we see a rocket humvee?
18) Could tanks crush trees?
19) How will you make the end of a map? Mountains? Invisible walls? Or damage over time when leaving the field? Or dead in … seconds?
20) How will water function? As a blocker which nobody could enters? As a damage dealer? Or will it be able to swim over? Or will there no water?
This sounds like you could now fill 2 episodes with my questions :P