Do not disagree about an up-grade at off-ball-LB. However, I think that's more of a Luxury than Need.
I agree that Landman is limited (I would say he's average) but most ILBs are limited in coverage; and Landman's extension pays him like a three-down-backer. If Darious Williams is let go (I expect that happen), Landman is currently scheduled to have the 3rd highest cap-hit among the Rams' defensive players.
Also agreed with you on Luther Burden (Ticky's grandson!). After Cornerback, I think the Rams' biggest Need is another Wide Receiver. Nacua and Adams are plenty, provided they do not miss games. When either is out, the Rams' wide receiver group is lacking, in my opinion. Adams is getting old; and the Rams were lucky (IMO) that Nacua was healthy for most of the season. The way he plays, durability should not be assumed.