ok,
1. the rats have not move the second time so they could not follow topaz
2. the rats could not get an attack of opportunity, i think .. .. .. i am correct, see spoiler
[sblock=swarm traits]
A swarm is a collection of Fine, Diminutive, or Tiny creatures that acts as a single creature. A swarm has the characteristics of its type, except as noted here. A swarm has a single pool of
Hit Dice and
hit points, a single
initiative modifier, a single speed, and a single
Armor Class. A swarm makes
saving throws as a single creature. A single swarm occupies a square (if it is made up of nonflying creatures) or a cube (of flying creatures) 10 feet on a side, but its reach is 0 feet, like its component creatures. In order to attack, it moves into an opponent’s space, which provokes an
attack of opportunity. A swarm can occupy the same space as a creature of any size, since it crawls all over its prey. A swarm can move through squares occupied by enemies and vice versa without impediment, although the swarm provokes an
attack of opportunity if it does so. A swarm can move through cracks or holes large enough for its component creatures.
[/sblock]
3. Tirgas might be getting a move action still, just asked the judge, but if any know for sure, speak up.