I've got a couple of comments.
First, congratulations! The Mega Der Red Max is a fun rocket! It has hi-drag design that makes for great low-and-slow flights. On G motors, you'll be able to easily watch the entire flight from launch to apogee and back down. You will never lose sight of it.
I think the packaging says the maximum altitude on recommended motors is 500 feet. That's not true. Usually Estes over-estimates max altitude, in my opinion, but this time they underestimated. I've seen the rocket push 1,000 feet on G motors, which is still not incredibly high, but it's certainly more than 500! Simulations will tell you what to expect for each motor, and I expect they will range from around 500 to 900 on G motors.
Because of the low altitude, you probably don't need the Chute Release. If you want to use it just for fun, then go for it. Just be sure you set the deployment altitude below the max altitude! In other words, don't set it for 500 feet if there is any chance the rocket won't reach 500 feet. An example would be if the G40 were siimmed to just around 500 feet, but it takes off in a low arc instead of straight up, then you might not reach the max altitude, and if you don't at least reach the deployment altitude, the Chute Release won't open. Honestly, if you think you will easily recover the rocket without using the Chute Release, then you might want to fly your first couple of flights without it. As you learn how the rocket flies, then you might want to give it a try.
There are a lot of Aerotech single-use G motors that will work great in the rocket. The G80 is fast and loud, and there is not much visible flame or smoke (it's great for fast, reliable launches, but I personally prefer more effects). G79 has white smoke and flame. G78 has green flame, plenty of smoke. G77 has a bright red flame. G74 is also white smoke and flame, but it's a small G, so it burns fast and won't go nearly as high as a G79. That's also a more affordable motor. All of those should have a good speed off the launch guide and result in a reliable flight.
There are two other Aerotech single-use motors that would be marginal. G40 has white smoke and flame like the G79 and G74, but it burns much slower, so it has lower thrust, but a longer burn time. That kind of flight really compliments the slow characteristics of the MDRM, so it can be great fun. But it also means the rocket takes off slowly and has the potential to arc over for a cruise missile type flight and crash! You have to be careful with that! I'd recommend you don't start with that motor, and if you do try it, use a long rail (not a rod), calm winds, and a large field with nothing to be damaged be an errant flight. The G38 is also in that class of low-thrust G motors, and would be risky. That motor makes thick black smoke.
So you have a lot of single-use motors to choose from. You would not go wrong with one each of the G77, G78, G79, G80 motors, and that would give you a taste of the different propellant types. And and if you get into reloadables, there are even more choices!
I'm thinking that for most of these motors, you might want a 4-second delay, not 7 seconds. You will need to run the sims with your finished built weight after decals and paint to be sure. Open Rocket will tell you the ideal delay for an ideal flight to apogee. Then you need to decide what fixed delay to pick, and it's never exactly right. You need to get close and consider whether to go long or short. So if the sim says the ideal is 6 seconds, then picking 7 is probably better than picking 4. But if it is closer to being right in the middle (5.5 seconds or less), I'd err on the side of going short and pick the 4-second delay. Rockets don't alway fly straight up, so sometimes they don't go as high as predicted, and they reach apogeee sooner than the simulation says. When that happens, shorter is better. Do your sims and use your best judgement.
Have a great time with your rocket!
