(All of these are pulled from here:
WotC Adventures)
Actually, Witching Season and Last Breaths came from the
free Dungeon magazine adventures page.
(As a possibly useful bit of info, of all the modules listed there by date, the module "City of Blood" from 05/09/2008 is D&D 3.5 edition, and so is everything earlier.)
Of the three modules you mentioned, it should be noted that all of them are for a level 6 party. So throwing those modules at a group of first-time 5th level players seems... hmm. I'd be sure to soften them first.
Anyway, at the location you pointed to (not the Dungeon modules, but the other free Wizards modules), there are three free fifth level modules. There is Base of Operations, which the OP already did. There is One Last Riddle, which strikes me as a terrible, terrible premise. That is, a super-powerful ghost asks a moderately powerful group to defeat a handful of weak enemies. And the question arises...
why doesn't the ghost just kick butt himself?!
However, there is a third fifth-level module there. That is, Fallen Angel. That one is actually pretty fun, but it's really hard to work in a plot hook. There is no treasure map, no long-standing feud, no enslaved city, etc. It's basically "something cool happened in a little town, isn't that nice?" That doesn't really cause players to pipe up and say, "Well, let's solve
that!"
I think having a religious person (paladin, cleric) receive a vision from the gods or the angels involved is a decent way to give the plot hook -- especially because you can make it a premonition of the very bad things to come. You could also handle it like traditional horror movie fare, and have a girl in another town (the town the PCs are in) become badly disturbed by horrific visions. Nothing will help -- the town cleric can't find a curse on her (so nothing to dispel) and can't understand what to do to end it. Enter the PCs.
Anyway, once you get past the problem of the plot hook, the adventure itself seems good.