For troops, 1 per 500 points is a good guideline. What you have sounds about right.
How much of everything in a
TAC list really depends on your local meta. As more stuff gets added to the game (flyers, superheavies, mega forts) it becomes a very difficult balancing act.
Generally, I like to have at least one fast melta unit. This can be bikes or speeders.
One of my core
tac squads is
MM/M with a combi-melta on the sarge points permiting. In either a rhino or pod.
I like to have at least some lascannons. Could be an auto/las pred, or a
TLLC/
ML dread.
Suicide drop still has a place. Ironclads or melta dreads, or sternguard with c-melta can work here.
At 2k I’d want to make sure I had around 3 solid answers for
AV 14 targets. And possibly a backup plan like a melta bomb stashed somewhere.
A lot of those things also work well for popping light/medium armor. But then you can also add some
MLs. And a lot of
AA stuff overlaps here as well. A quadgun from an
ADL or a stromtalon do a number on light tanks. TML/
HBs work well for both light armor and hordes.
One of the tricks is redundancy and overlap whenever you can. But you have to be careful about paying extra for stuff you don’t need.
I’d recommend going over to the army list section and pokeing around. There are a lit of different design philosophies, so take everything with a grain of salt. But it does offer a perspective on how other people play.
I’m a fairly casual guy, but here are links to two of my latest 1,850 lists, not 2k, but should give you an idea on how I balance things.
Vs. nids
Last tournament