I second the notion of just chopping off bolt pistols from the hands and gluing a bolter in its place. Even for someone as unrefined as myself it comes out far more effective than you'd think and after even a coat of primer it looks like it came out of the box that way.
As for loadout...
I would say 98% of the time you'll want jump packs: they just give way too much utility, whether on the board, using Forlorn Fury (that extra 12"+D6" movement before the game starts instead of 6" + D6") or being able to use Descent of Angels. There are certainly ways to use them without Jump Packs, but you gotta be sure you have a concrete plan that is more reliable and efficient then jump packs.
Weaponry = that old saw of "depends on the rest of your list." I generally like 2-3 Power Fists and then 1-3 Power swords in a unit of 15, but it comes down to points of course. I like being able to threaten anything with fists, but they are not my go-to unit for taking out big scary things. If I run both Sanguinary Guard AND Death Company (in theory it works, but only tried it once) then DC will be nothing but bolters and chainswords since they then fill the role of dedicated horde-sweeper.
Thunder hammers can work (YMMV of course), but were I to run them, I would do 5x TH DC dudes in a Stormraven. Otherwise I like bolters so you can "John Woo" it by shooting target A and charging target B.