Hey and welcome to the Imperial Guard!
I agree with everything Gorgosaurusrex said. Though, personally, I'd also remove the melta bombs. You probably won't ever really get close enough to vehicles to make those points worth it.
I'd also remove the standards. They just don't do enough for their points.
I like the amount of infantry and tanks you have, though I'd suggest maybe swapping a couple of the platoon squads for veterans in chimeras. This allows you to drive up the board with some good units to cap objectives or harass your enemy before they reach your gun line. Arming them with meltas or plasma is best, 2-3 in each squad, depending on if you want them to be anti-tank or anti-elite (space marines and the like). And keeping some of the platoon guard in allows you to keep some cheep gun line units.
As Gorg said, to make prime use of all that armour, you'll probably want a second
CAD (combined arms detachment) of guard that you ally together to make one army. There are two reasons for keeping all your armour pieces separate: 1) If one tank is hit in the squadron and is blown up, all remaining hits move over to the other vehicles in the squadron, allowing what would've only blown up one vehicle blow up several. 2) So that each vehicle can shoot at separate targets, and aren't stuck shooting at whatever the first shoots at.
I'd probably make the list look something like this, going by things you already have:
-CAD1-
HQ
-
CCS with Master of Ordinance
TROOP
- 20 man platoon with heavy weapon team
- 20 man platoon with heavy weapon team
HEAVY SUPPORT
- Leman Russ
- Exterminator
- Vanquisher
-CAD2-
HQ
- commissar
TROOP
- Veterans with plasma guns in chimera
- Veterans with plasma guns in chimera
HEAVY SUPPORT
- Basilisk
- Basilisk
- Demolisher
With the addition of veterans in chimeras, you may need to drop a few things, maybe a basilisk, and while having the two platoons don't allow you to blob them all together, that might be a good thing. If you can find the points to make the commissar a lord commissar, I'm pretty sure he has an aura around him with his special rule that makes the guard run less. So he can effect more than just the unit he's in. Having a huge blob is cool, but if they do eventually run, that's your entire force running off the board together. Split up into blobs of 20 means only 20 will run at a time (if they fail the emperor and flee).
Hopefully this helps