Grundar

I'm no tech guru, but from my understanding, you need the transfer speeds of an SSD device for DCS (and arguably for all of modern gaming - depending on the genre).  The retrieval speeds are significantly faster than a standard HDD = faster and more stable loading of data.  As Max points out, old style spinning plate HDD's are too slow, you simply will have delays loading in all that data and you see that reflected in the differences between the drives and your games performance.  You turn the radar off and it improves a bit and that is because less data is having to be retrieved.
If you are stuck with a HDD you can perform a defragmentation of it to clean it up (Don't defragment a SSD device though!) and maybe speed it up some.  It won't hit anywhere near SSD performance but it might help some.  Another thing you could review your pagefile and move it to the SSD if required, you could also increase the size of it if needed. While this gives you theoretical "extra RAM" it may give you a performance increase, especially if your pagefile is on the HDD instead.   
Other things you could try (I'm not entirely sure if it is useful with DCS)  but with some games increasing some display settings to higher settings will push workload onto the GPU and off of the CPU which can help increase general performance at times, if the CPU is under constant high loads.  There are some DCS performance guides around a quick search reveals this one: 
I haven't used it myself so not sure if it would be beneficial to you or not.
 
Long Story short, get another or a larger SSD if you can and shift DCS and it's maps to SSD drives only. If you can't maybe some of the above can ameliorate some trouble for you. 

So after you have started up the aircraft and are all good to go, make sure you are tuned into the correct radio channel, I think on this mission you (the pilot) need to select channel 2.   Then pressing the spacebar should activate the next steps (radio messages) and trigger the mission progress.

As in you simply want to bring up the display?  There is a switch located down at the bottom on the Pedestal Panel (located behind the flight stick) next to the accelerometer. The switch allows you to flick between Radar, Off, TV.  Flick it up for Radar.
Edit: Manual Link https://f4.manuals.heatblur.se/cockpit/pilot/pedestal_group.html

So I gave this a test following the procedures as listed in the manual.
Flight Controls Check
The Crew Chief should confirm all flight control positions. Slats and Flaps should be OUT AND DOWN.
Pitch trim - 1 TO 3 UNITS NOSE DOWN Control stick - PULL FULL AFT AND RELEASE Movement forward should be smooth and free of any restriction. The stick may not return to the full forward position. The stick should move forward at least to the ½ travel position and further movement toward the stop should require no more than one pound push force. (Chief should report stabilator positions) Rudder - CHECK FULL TRAVEL LEFT AND RIGHT (Chief should report rudder positions) Ailerons/ARI - CHECK Move control stick full left. Confirm left spoiler up, right aileron down and rudder slightly left. Engage yaw stab aug. Confirm rudder move further left (Chief should report "KICK"). Depress emergency quick release lever. Confirm rudder move toward neutral (Chief should report). Release emergency quick release lever, neutralize stick and disengage yaw stab aug. Repeat check substituting right for left On the Ailerons check as via the aforementioned procedure I was able to get the confirmation of rudder kick and rudder neutral when using the emergency quick release lever on both right and left sides. 
But if i tried to do it fast it did seem to not report the rudder position consistently, I think I must of been cutting the crew chiefs replies and the crew chief stopped responding to that first input and then went to respond to the next? - I guess that interrupts and prevents that sequence of action and reply/response?  When I deliberately paused for a few seconds between each step it reported correctly each time. So for me; that was stick full left - crew chief confirms, wait a few seconds Stab Aug Yaw on - crew chief confirms the kick, wait a few seconds and then squeeze the emergency quick release lever and hold - crew chief reports neutral.  Centre stick, Stab Aug Yaw off, then repeat for the right side and it worked fine. 

Yeah Jester can't monitor the fuel, there are no such gauges in the WSO cockpit which is why he will prompt you regarding fuel at times.  Well technically Jester will know when you are very low fuel when the Master Caution light illuminates at critically low fuel levels.
Diesel Thunder has a wonderful video regarding the Fuel System and Management: 
 
Personally what I do is factor in the following;
Total Internal Fuel = 12000lbs of Fuel (fuselage and wing tanks)
External Fuel:   Centerline Tank = 600 Gallons of Fuel - equivalent to 4000lbs of fuel.
                         Wing Tank (always carried in pairs) 370 Gallons of Fuel per tank = 740 Gallons which is equivalent to 4800lbs of fuel (2400 per tank).
Total Fuel (Internal and Centerline tank): 16000lbs
Total Fuel (Internal and External Wing Tanks):  16800lbs
Maximum Total Fuel (Internal, Centreline and Wing Tanks): 20800lbs of fuel.
 
I check what I have before take off to make sure I have the correct values and then I will reference the Fuel Totalizer for status.  It registers only internal fuel so I make sure that I am using any external tanks early, especially the centreline tank which obstructs the operation of any front fuselage mounted Aim-7's.  I reference the Fuselage Fuel Tape to determine if i have empty internal wing tanks or not to get an idea where I am sitting at.
I also pay attention to the fuel flow gauge.
- This gauge does not display extra fuel consumption via afterburner use, you have to watch your Fuel Gauge totalizer spin lol.  But for approximation I multiple your current PPH x4 to estimate fuel usage in afterburner.
So knowing that I am using external tanks first and that I can drop them if necessary also means later on I am seeing a complete fuel remaining picture without having to reference back to external tanks etc.. It also means i can jettison them in combat if required without worrying about having a sudden big reduction in available fuel.
One caveat is that you have to monitor when your external tanks are empty so you can move the switch around as necessary, especially given that selecting external tanks prevents any flow from the wing tanks until deselected.
So when Jester inevitably asks me how is our fuel status I'm much more confident in giving him a more accurate answer rather than fobbing him off lol.

Ok Salvo mode does what you are looking for and it will launch from all pods, continuous won't, not sure if that is a design feature of that mode.
Edit: On the AWRU I had it set to salvo (S) and had the Interval in a normal mode, bomb depress then emptied all my pods.