Is there any way to adjust the radius of the D.VA bomb or the damage of it?
I don’t think you can do the radius easily, although you could use Start damage modification for anyone outside your desire radius to zero, for the duration of the ult (bare in mind this would make you unable to attack them with baby dva, although there could be other things that you could do), and for the damage kind of the same really… although now that I think about it isn’t as easy as this, since you can’t really retrieve the mech’s coordinates.
Even though this is a pretty reasonable request I think this is a pretty hard problem with the tools we have at the moment. I don’t want to say that it’s impossible because it’s probably not but it will be very difficult. 
I don’t think there is a way to reference the position of the D.va mech once D.va has ejected. This makes it difficult to modify the radius. You can try to replicate the flight path yourself, but unlike other ults/projectiles the path it takes is a bit weird (D.va’s ult travels the same path she would had she stayed in her mech and boosted without moving the mouse, it can also have some strange interactions with map geometry).
Maybe in the future they’ll add a way to reference her ult location.
In terms of damage you could turn up the amount of damage a D.va player does with the SET DAMAGE DEALT action. Unfortunately, the dropoff for her ability would still be active. We also do not have a good way of determining how a player was damaged yet so this damage increase would be the same across all of her abilities. Which may or may not be good enough for you.
There are two remedies to this that I can think of. One thing you could do is determine that D.va has used her ult and ejected from her mech, (I believe I have seen ways to do this on this forum) disable her primary fire, and increase her damage when this happens. That way her out of mech blaster wouldn’t be overpowered when she ejects but she would be utterly defenseless when she ults. You could also try timing the ult by adding a WAIT for 2.4 seconds instruction before the SET DAMAGE DEALT and then setting the damage back to the normal value after another .2 second wait period since the mech explodes 2.5 seconds after she presses q.
Is there no way to set damage for specific abilities? Like make her micro missles do more? I have been tinkering with it but can’t figure anything out
The problem is that a lot of D.va’s abilities are affected by drop-off and don’t deal a set amount of damage.
EDIT: I read your question wrong. Unfortunately you’re right, there is no easy way to adjust the damage for specific abilities. You have to be able to detect abilities through damage profiles as you suggested earlier. Which is tough or possibly impossible for D.va due to her damage variability.
I hope they fix that soon, i feel like it should he an easy fix
another annoying part about detecting which ability is used based off the damage it does is that there are several modifiers in the game that change damage.
for example, damage reduction from shield, during roadhog’s healing, nano boost damage reduction, etc.
but it’s what we have to work with at the moment…