Yes, those are boosted by levelling up the summon skills (see the descriptions in the
DKS FAQ/Guide). Also, once you get the creature (available from about level 10 or 12), having the cooldown on a summon is not as big a deal, since you would still have some support.
BTW, when you edit a post, there is a 'Delete Post' button beside the 'Change Post' and preview buttons, which will remove the topic, as well (as long as nobody replies to it).